Discrete event simulation as a tool for
virtual commissioning
Using a discrete event simulation model as a base for gener-
ation and verification of rudimentary PLC logic

Master’s thesis in Production Engineering

Marcus Andersson
Atle Zvantesson

Department of Electrical Engineering
CHALMERS UNIVERSITY OF TECHNOLOGY
Gothenburg, Sweden 2018





Master’s thesis 2018:EENX-30

Discrete event simulation as a tool for virtual
commissioning

Using a discrete event simulation model as a base for generation and
verification of rudimentary PLC logic

Marcus Andersson
Atle Zvantesson

Department of Electrical Engineering
Division of System and Control

Chalmers University of Technology
Gothenburg, Sweden 2018



Discrete event simulation as a tool for virtual commissioning
Using a discrete event simulation model as a base for generation and verification of
rudimentary PLC logic
Marcus Andersson
Atle Zvantesson

© Marcus Andersson & Atle Zvantesson, 2018.

Supervisors:
Henrik Carlsson, Volvo Cars
Maria Ludvigsson, ÅF

Examiner:
Petter Falkman, Department of Electrical Engineering

Master’s Thesis 2018:EENX-30
Department of Electrical Engineering
Division of System and Control
Chalmers University of Technology
SE-412 96 Gothenburg
Telephone +46 31 772 1000

Cover: Picture showing parts of an electric monorail system modelled in Plant
Simulation.

Typeset in LATEX
Gothenburg, Sweden 2018

iv



Discrete event simulation as a tool for virtual commissioning
Using a discrete event simulation model as a base for generation and verification of
rudimentary PLC logic
Marcus Andersson
Atle Zvantesson
Department of Electrical Engineering
Chalmers University of Technology

Abstract
Virtual commissioning is growing more popular in industry today, as it allows com-
panies to develop their production quicker and at a lower price since changes can be
tested and evaluated without stopping the real-world system. Virtual commission-
ing is used for many different applications and projects. The purpose of this thesis
is to evaluate if the discrete event simulation (DES) program Plant Simulation can
be used as tool for virtual commissioning of Programmable Logic Controller (PLC)
code.
This will be tested by modelling an electric monorail system, with a line at Volvo
Cars Torslanda plant used as a reference. This digital twin will be used as a base
for the design of the monorail control system. The model will at the same time be
connected and controlled by a virtual PLC to make sure that the logic works as
intended. Testing of the PLC code against the Plant Simulation model will be done
continuously as new functionalities are added. In the end the whole model should
be controlled by the PLC rather than the internal logic.
The next step is to investigate if and how the PLC code can be automatically gen-
erated based on data from the Plant Simulation model. This is achieved by creating
a library in the PLC of all relevant functions that is needed to control the monorail.
This library is then used to create function block instances for every rail in the Plant
Simulation model.
What follows then is a summation of the method results, as well as a list of improve-
ments that would allow Plant Simulation to get a more widespread use as a virtual
commission tool.

Keywords: Virtual commissioning, Discrete event simulation, PLC code auto gen-
eration, Plant Simulation, TIA Portal Openness

v





Acknowledgements
We would like to thank everyone who was supported us and our work during this
project. However, we would also like to thank the following people a little extra (in
no particular order):

• Henrik Carlsson at Volvo Cars for pointing us in the right direction and
helping us when we got stuck.

• Maria Ludvigsson at ÅF for being a great mentor who answered every
question we asked and who kept us pushing forward

• Pär Ström at ÅF for helping us to find a topic that both we and our stake-
holders found exciting

• Johan Nordling at Siemens for helping us with the licenses for the TIA-
portal and PLCSIM Advanced

• Hans Sjöberg at Chalmers University for helping us with all licensing trou-
bles encounterd in the start of the project

• Eduard Kapoun at Summ Systems for helping us understand the connection
between Plant Simulation and PLCSIM Advanced

Finally we would also like to say thanks to Petter Falkman for his role as the
examiner for this project.

Marcus Andersson and Atle Zvantesson, Gothenburg, 2018

vii





Contents

List of Figures xi

List of Tables xiii

1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Aim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Research questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Theory 3
2.1 Virtual commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Discrete Event Simulation . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2.1 Technomatix Plant Simulation . . . . . . . . . . . . . . . . . . 4
2.3 PLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3.1 PLC Programming languages . . . . . . . . . . . . . . . . . . 5
2.3.2 STEP 7 TIA Portal . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3.3 PLCSIM Advanced . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3.4 TIA Portal Openness . . . . . . . . . . . . . . . . . . . . . . . 7

2.4 Open platform communication . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Electric Monorail System . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.5.1 Volvo Cars EMS . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.6 Previous research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 Methods 10
3.1 Connecting Plant Simulation and PLCSIM

Advanced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.1 Creating the connection . . . . . . . . . . . . . . . . . . . . . 10
3.1.2 Sending data . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.3 Building the test model . . . . . . . . . . . . . . . . . . . . . 12

3.2 Coding with a standard . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.1 Plant Simulation standard . . . . . . . . . . . . . . . . . . . . 14
3.2.2 PLC standard . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.3 PLC hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3 Modelling the EMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 Auto-generation of PLC code . . . . . . . . . . . . . . . . . . . . . . 18

ix



Contents

4 Results 20
4.1 Hardware differences between PLC:s . . . . . . . . . . . . . . . . . . 20
4.2 Lack of detail in Plant Simulation . . . . . . . . . . . . . . . . . . . . 20

4.2.1 Measurement problems in EMS . . . . . . . . . . . . . . . . . 20
4.3 Slowdowns when running Plant Simulation

with a virtual PLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4 Connection between Plant Simulation and

TIA Portal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.5 Creating the PLC code . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.6 Lack of documentation . . . . . . . . . . . . . . . . . . . . . . . . . . 22

5 Conclusion 23
5.1 Improvement potential in the software . . . . . . . . . . . . . . . . . 23
5.2 Limitations of the connection between Plant Simulation and PLC . . 24
5.3 The extent to which PLC code can be

designed based on a Plant Simulation model . . . . . . . . . . . . . . 24
5.4 Future research topics . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5 Closing statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Bibliography 26

A Connecting PLCSIM Advanced to the TIA Portal I
A.1 Setting up the Virtual PLC . . . . . . . . . . . . . . . . . . . . . . . I

A.1.1 Using the Virtual Ethernet Adapter . . . . . . . . . . . . . . . II
A.2 Configuring TIA for simulation . . . . . . . . . . . . . . . . . . . . . II
A.3 Connecting and downloading to the virtual PLC . . . . . . . . . . . . II
A.4 Converting 300 code to 1500 . . . . . . . . . . . . . . . . . . . . . . . III

B Connecting Plant Simulation to a virtual PLC VI
B.1 Setting up the connection . . . . . . . . . . . . . . . . . . . . . . . . VI

B.1.1 Sending data to the PLC . . . . . . . . . . . . . . . . . . . . . VIII
B.1.2 Receiving data from the PLC . . . . . . . . . . . . . . . . . . IX

B.2 Connecting to a remote virtual PLC . . . . . . . . . . . . . . . . . . X
B.3 Understanding the data exchange interval . . . . . . . . . . . . . . . XI

B.3.1 Notes regarding the data exchange . . . . . . . . . . . . . . . XII

C Control logic of the test model XIII

D SIMTALK code for exporting data XVI

E XML code for safety zone 320 XX
E.1 Results from imported code . . . . . . . . . . . . . . . . . . . . . . . XXII

F PLC Standard XXXII
F.1 Behavior of the Function Blocks in GlobalLib . . . . . . . . . . . . . XXXII

x



List of Figures

2.1 The connection between PLCSIM Advanced Runtime Instance on one
PC to the STEP 7 TIA Portal on another PC[7]. ) . . . . . . . . . . 6

2.2 Overview of the EMS line. The assembly station is located in the
lower left corner. Notice the XC90 track in black and the V90 track
in green. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.1 The dialog window of the PLCSIM_Advanced object in Plant Simu-
lation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.2 A table showing all IN-signals to the PLC as well as their aliases and
connected model attributes . . . . . . . . . . . . . . . . . . . . . . . . 12

3.3 3D view of the model used to test the connection with PLCSIM Ad-
vanced. The Connection is set up with the PLCSIM object on the
left of the line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.4 A Plant Simulation Toolbox with nine different types of rail . . . . . 14
3.5 The function block library in the PLC . . . . . . . . . . . . . . . . . 15
3.6 An example of a rail control Function Block, showing the blocks in-

puts to the left of the block, and outputs on the right side of the
block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.7 A graphical representation of the differences between two instances
of the same rail type. . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.8 A graphical representation of the hierarchy of the PLC program. The
main block can not communicate directly with the function blocks.
However, blocks on the same level depend on information from each
other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.9 2D view of a part of the Pant Simulation Model. The coloured back-
grouds represents different safety zones . . . . . . . . . . . . . . . . . 17

3.10 The PLC template for an ACC network with generic signals and
variables at the connections instead of instance specific ones. . . . . . 18

3.11 A text-file a list of all rails in safety zone 340, and a list of all XML
templates used for autogenerating a new PLC code. . . . . . . . . . . 19

4.1 An error prompt in Plant Simulation. There are no available docu-
mentation on why this error occurs or how to fix the problem. . . . . 22

A.1 The PLCSIM Advanced Interface for Online Access and TCP/IP com-
munication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I

xi



List of Figures

A.2 The Start tab in PLCSIM Advanced showing the an example of in-
stance name and the correct IP address and Sub-net mask. . . . . . . I

A.3 The PLCSIM Advanced Interface. . . . . . . . . . . . . . . . . . . . . II
A.4 Showing the Siemens PLCSIM Virtual switch protocol installed on

the physical Ethernet adapter Inter(R) Ethernet Connection and the
Siemens PLCSIM Virtual Ethernet Adapter in the Network Connec-
tions list in the Windows Control Panel. . . . . . . . . . . . . . . . . III

A.5 Showing where to find the project properties menu. . . . . . . . . . . IV
A.6 Showing where to check Support simulating during block compilation

in the project properties menu. . . . . . . . . . . . . . . . . . . . . . IV
A.7 Showing how to search for devices in the TIA Portal. . . . . . . . . . V
A.8 Showing the Extended donwload to device window in the TIA Portal. V

B.1 The Manage Class Library screen. Activated objects have a ticked
checkbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI

B.2 The toolbar in Plant Simulation with the PLCSIM_Advanced object
selected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII

B.3 Figure showing how to connect the PLCSIM_Advanced object to the
virtual PLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII

B.4 A table showing all IN-signals to the PLC as well as their aliases and
connected model attributes . . . . . . . . . . . . . . . . . . . . . . . . VIII

B.5 Two OUT-signals connected to a method and a global variable re-
spectively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IX

B.6 Figure showing how to input the address and port number when con-
necting to a remote virtual PLC . . . . . . . . . . . . . . . . . . . . . X

B.7 Figure showing the data exchange interval fields in the PLCSIM_Advanced
object and the item groups . . . . . . . . . . . . . . . . . . . . . . . . XI

C.1 The PLC code used for controlling the test model . . . . . . . . . . . XIV
C.2 The list of IN-signals and their connections in Plant Simulation . . . XV
C.3 The list of OUT-signals and their connections in Plant Simulation . . XV

E.1 The resulting PLC code, in ladder logic, for safety zone 320 . . . . . . XXXI

xii



List of Tables

3.1 The four categories of signals that can be imported to Plant Simulation 10
3.2 Benefits and drawbacks of using different standards . . . . . . . . . . 14
3.3 The function of the rail control Function Blocks I/O signals . . . . . 16

xiii



1
Introduction

Virtual commissioning is becoming a more and more popular tool for companies that
want to expand or change their production. Proper use of Virtual commissioning
reduces both the cost and time needed to implement large-scale changes. Changes
to existing lines and factories can be evaluated without stopping production and
layouts for new factories can be designed and tested in the virtual world before the
physical factory has been constructed.

1.1 Background
At the plant in Volvo Cars Torslanda there is an Electrical Monorail System (EMS)
used in production with PLC control. As well as functional PLC code there also
exists an DES model used for production flow simulation. However the current DES
model is independant of the PLC as can hence not be used for Virtual commissioning
of the PLC.
Today there exists a multitude of programs for virtual commissioning of production
cells and shorter lines, such as Process Simulate and Robot Studio, but no tool
for larger scopes. Volvo Cars, together with ÅF and Siemens, wants to evaluate
whether or not the discrete event simulation program Plant Simulation can be used
as such a tool. The general idea is to use the Plant Simulation model as a base
for the development of the PLC control logic for the real system. The code should
not create the whole program at once, but should instead be scalable enough for
continuous development during the design of the production.
If successful, it means that the general design of the control program can be created
in the early design-stages of a project, thus shortening the development time and
lessening the workload of the PLC programmers. It could also introduce new ideas
to the line-builders if the PLC engineers are involved in parts of the decision making,
i.e. designing the production system and the control logic together. This plays in
to a broader push in industry of having cross functional teams and involving more
functions earlier in new projects.
If the connection between Plant Simulation and the PLC is successful it would also
be useful to find out to which extent the PLC code can be auto-generated. The code
should then preferably be created based on information from the Plant Simulation
model. The best-case scenario would be if the PLC code were continuously updated
in conjunction with changes in the Plant Simulation model.

1



1. Introduction

1.2 Scope
The primary focus of the model will be the monorail itself. Modelling switches, junc-
tions and stations will have a lower priority. Information such as process times for
machines, the total number of hangers and breakdown data will be largely ignored,
as the aim of the project is to evaluate the connection between Plant Simulation
and the PLC rather than production flow analysis. Furthermore, the real EMS line
contains a service station that will not be modelled, as breakdowns of the hangers
will be ignored.
The PLC code will control an EMS line according to a standard but not feature any
alarms or HMI:s.

1.3 Aim
The primary goal of this project is to evaluate if and how a discrete event simulation
model can be used for designing or creating PLC code. A secondary aim of auto
generation of the PLC code was added later a supplement to the main question.

1.4 Research questions
This project can be summarised by a research question, that will help focus the
work to specific areas:
How could a DES program be used by engineers as a tool for virtual
commissioning of PLC?
The question can further be split into three sub-questions:

RQ1 What limitations are there in the connection between Plant Simulation and
PLC?

RQ2 To which extent could such a code be programmed, i.e. which abstraction
level is appropriate?

RQ3 What is needed in the future for Plant Simulation to get widespread use for
this type of application?

These questions will be handled throughout the thesis and further investigated in
section 5.

2



2
Theory

2.1 Virtual commissioning

Virtual commissioning is a method of simulation models to test interfaces between
software and hardware to identify and address design flaws and errors. As vir-
tual commissioning can be performed without the usage of the physical system or
hardware, the commissioning can be performed earlier on in the project before the
physical system is completed. The fact no physical resources except a PC are nec-
essary for virtual commissioning means that several different physical layouts and
systems can also be tested without the additional expenses.
Proper use of virtual commissioning allows companies to design and evaluate changes
quicker, while still having the production up and running. Virtual commissioning
is becoming a more and more popular tool for companies that want to expand or
change their production.

2.2 Discrete Event Simulation

Discrete event simulation (DES) is a tool that allows its users to quickly simulate
and analyse many different scenarios in a short span of time. As the name suggests,
events in such a system occur at discrete points in time, when they trigger a change
in the system. No changes can occur in the system without an event triggering it,
so the program only needs to model the events and not the time between events [1].
Such a system takes less processing power to simulate than a continuous system, as
non-valuable time is ignored.
A DES model is made up of several structural components including, but not limited
to: entities, attributes,list and queues, events and Activities [1, 2].

• In a DES model, entities are the only objects that cause any changes in the
system. Entities represents all objects that requires explicit representation in
a system, such as machines, products, workers and transports [1].

• Attributes are properties that describe entities. The name of an entity is a
common attribute found in most entities, while an attribute like colour or size
is more often found in products.

• Lists and queues are used to order entities according to certain attributes, such
as creation time or type. Queues can also be used in buffers in to simulate
ordering systems, such as first-in-first-out.

3



2. Theory

• An event is simply a change in a system. If no event is happening the system
doesn’t change.

• An activity on the other hand is made up of two events that mark the start
and end of an operation that changes the state of an entity, such as a product
being processed in a machine.

2.2.1 Technomatix Plant Simulation

Plant Simulation works in a similar way to many other DES-programs in that enti-
ties move around a system, creating new events every time a change of state happens
at any place in the simulation. The moving entities in Plant Simulation generally
belongs to the class Manufacturing Units, commonly referred to as MU:s. MU:s in
a system usually represent products, parts, containers or transporters.
MU:s can move around the system in a few different ways, most commonly by lines,
tracks or transporters. Line and track entities can represent a multitude of different
conveyor types, while transporters can represent vehicles such as AGV:s and fork-
lifts. Lines and tracks can be connected to a single machine or track to simulate
one-piece flows, or to several different objects in order to create more complex sys-
tems. Furthermore, sensors can be attached at any point of a line or track. These
sensors can then be connected to attributes in the passing MU or methods that will
be executed when the sensor is triggered.
Plant Simulation follows an object-oriented logic, similar to other programming
languages such as Java and C. This hierarchy allows users to address objects by
following its file-path [3]. Furthermore, each entity possesses several attributes that
describe the state of said entity. Most attributes are shared between different entity
types, while others are specific to certain classes. An example of common attributes
shared by all entities is names and classes. Some attributes are more specific to
certain entities or classes. A machine, for example, also contains attributes that de-
scribe set-up and process times, while a MU has instead has attributes that describe
its destination and colour.
One of the most useful objects i Plant Simulation is Methods. Methods are written
in Siemens’ own coding language SIMTALK and are used to control the simulation.
A SIMTALK method could for example be used to determine the destination of an
MU depending on a certain attribute, or change the speed of a conveyor.
In Plant Simulation there are several ways of triggering a SIMTALK method: a
method can, for example, be used as an entrance- or exit control in a processing
entity. A method can also be called from another method, which sometimes requires
parameters, similar to subroutines in other coding languages.
A Plant Simulation model can be created in both 2D and 3D. Generally, a 3D en-
vironment requires much more processing power to simulate compared to a 2D one.
However, a 3D environment gives users and observers a better understanding of the
relationship between the model and the reality. Plant simulation can seamlessly
switch from a 2D to a 3D model and vice versa, so it is possible to build the system
in 2D and then adjust the positions and geometry of machines and conveyors in the
3D space to create a more accurate model of the real system.

4



2. Theory

2.3 PLC
Programmable Logic Controller (PLC) are often used in industry to control manu-
facturing equipment and robots in the factories. The PLC were introduced to replace
relay and timer systems [4]. However the PLC is more flexible then the old relay-
systems and can be reprogrammed to a different behaviour and signals response by
just uploading a new code, rather than changing the connections of cables as in
the old relay system. A PLC consists of multiple parts, a Central Processing Unit
(CPU), interface for communication, an I/O, a programming unit, power-supply
and memory unit [5].
The CPU contains one or more microprocessors that reads inputs signals and com-
putes the correct output using the program stored in the memory unit. The commu-
nication interface allows the PLC to communicate in a network with other hardware.
In such a network the PLC can collect data, handle synchronisation, verify other
hardware and connections. The programming unit is used to write programs that
can be transferred to the memory unit. The programming interface can be a small
display with buttons for input, a terminal with a keyboard, or more commonly
today, a PC connected to the PLC from which the code is downloaded to the PLC.

2.3.1 PLC Programming languages
PLC can be coded in 5 different languages following the IEC61131-3 standard [6].
Structured text and instruction list are text based languages, and while they are
more easily auto-generated they are less graphical and harder to follow by operators
without text based coding experience . Ladder diagrams, Functional Block Diagrams
and Sequential Function Charts are all graphical languages which makes them easier
to follow in real time. Ladder coding follows the structure of an old relay diagram
and is and as such easier to use by operators with previous experience in relay design.

2.3.2 STEP 7 TIA Portal
STEP 7 TIA Portal is an software engineering tool for SIMATIC PLC:s. It’s both
a programming interface for PLC:s and a system and diagnostics tool for both real
and virtual PLC controllers.

2.3.3 PLCSIM Advanced
PLCSIM Advanced is a simulation software that is capable of emulating the be-
haviour of a SIMATIC 1500 series PLC. The software has a direct interface between
STEP 7 TIA Portal, Plant Simulation and also Process Simulate which allows it to
control simulated objects as if they were controlled by a real 1500 PLC.

5



2. Theory

PLCSIM Advanced has two settings, Local and Virtual Ethernet TCP/IP. Local
creates a soft PLC on the computer that is only accessible on the host computer.
By using the virtual Ethernet TCP/IP mode the soft PLC is accessible on any
network the host PC is connected to. Virtual Ethernet TCP/IP allows the PLC
simulation to be run on a different computer than than the TIA portal and or Plant
Simulation and hence in theory should allow increased performance (less computing
time) since the simulations and interfaces are divided up between several hardwares.
When running Plant Simulation on one computer and PLCSIM Advanced on an-
other distributed communication via TCP/IP is used. The Simulated PLC runtime
instance connects to PLCSIM Virtual Ethernet Adapter through PLCSIM Virtual
switch, that in turn connects to the PCs Ethernet Adapter. Plant Simulation or
STEP 7 on the client PC connects to the Host PCs Ethernet adapter via normal
Ethernet TCP/IP communication, which in turn relays the connection to the PLC
as shown in figure 2.1.

Figure 2.1: The connection between PLCSIM Advanced Runtime Instance on one
PC to the STEP 7 TIA Portal on another PC[7]. )

The version used in the project, PLCSIM Advanced V2.0 has the capability to em-
ulate 2 different families of PLC CPU:s, the SIMATIC ET 200 SP series and the
SIMATIC 1500 series. However the version used at Volvo for the specific EMS used
in this project is a 300 series, which means that the current code can not be directly
run with PLCSIM Advanced without major changes of the code, as some functions
aren’t cross-compatible between the two series.

Virtual time

The virtual CPU have two clocks, a virtual and a real clock. The virtual clock
controls cycle times and time measurements in the PLC, while the real clock is
used for communication with STEP 7 and the PCs Operating system. Virtual time
scaling means the virtual clock is speed up to a 100 times faster than real time. This
does not change the execution speed of the program, but change how frequently the
main program is executed. If the PC is incapable of executing main before the next
scan cycle, the virtual controller goes to STOP mode.

6



2. Theory

Freeze state of the virtual controller means that the virtual clock stops, the execution
of the program stops but the virtual controller is still accessible from the TIA Portal.
In the freeze mode the CPU is still in RUN mode, just waiting for a synchronisation
point from other simulation partners.

2.3.4 TIA Portal Openness
TIAPortalOpennessDemo is an open source application for windows that connects to
the STEP 7 TIA Portal via the TIA Openness protocol. TIAPortalOpennessDemo
has a user interface that allows the user to manually import blocks PLC code from
an XML file into the project in the TIA Portal, or export PLC code blocks to XML
files [8].

2.4 Open platform communication
OPC is an industry standard for communicating between software applications and
industrial control hardware. This allows production systems modeled in DES appli-
cations such as Tecnomatix Plant Simulation to be controlled by a PLC controller.
By emulating the control and communication behavior of the physical system the
simulation model can be used for virtual commissioning of the PLC code.
The OPC interface between the PLC and simulation model can affect the behav-
ior and accuracy of the simulation due to Free-wheeling and synchronization issues
[9]. However, a previous master thesis by Engström and Liao [10] has shown that
a model built in the DES software Siemens Plant Simulation software can be con-
trolled by a PLC through an OPC protocol without any negative effects on accuracy,
given that the simulation is run in real-time. PLCSIM Advanced has a direct in-
terface with Plant Simulation that allows faster-than-real-time simulation without
synchronization issues.

2.5 Electric Monorail System
An electric monorail system (EMS) is transport system with rail going independently
controlled vehicles, also referred to as hangers. Switch points are used to allow the
vehicles to change lines. The track is either mounted hanging from the ceiling or a
steel structure leading to an unobstructed factory floor [11]. EMS are commonly used
in automotive industry to carry parts such as chassis and doors between assembly
stations.

2.5.1 Volvo Cars EMS
The monorail system at Volvo is used for transporting the car sides from the body
side line to the framing line where it is joined to the floor of the car. The layout of
the line can be seen in figure 2.2. The hangers picks up a right and a left side for
either a XC90 (black track) or a V90 (green track) and then drops them off at an
assembly station.

7



2. Theory

Figure 2.2: Overview of the EMS line. The assembly station is located in the
lower left corner. Notice the XC90 track in black and the V90 track in green.

The monorail system and the hangers are controlled by an PLC using three control
rails. These three rails are the power, presence and command rail. When the power
rail is enabled by the PLC it powers on the hangers and allows them to travel. The
presence rail detects any hangers on the rail and signal the presence of a hanger to
the PLC. The command rail gets a speed command from the PLC that any hangers
on the rail will follow.
The monorail is separated into several distinct "cuts", both figuratively and literately.
Each cut has a specific function following the outlines in Volvo Cars internal standard
for electric monorail systems [12]. For example: an accumulator rail (or ACC-rail)
can have several hangers on it and thus works as a buffer, while a transport zone
(TZ-rail) only allows one hanger at a time and is used in corners and other places
where there is a risk of collision. A group of cuts are further grouped into different
"safety-zones", each with their own HMI:s and safety PLC:s. This ensures that parts
of the line can still function even if there is a problem in a zone.

8



2. Theory

2.6 Previous research
The idea of having a digital twin of a line or factory that evolves as the project
progresses has been discussed for at least a few years, with [13] describing how such
a system could work.
As virtual commissioning is becoming more and more relevant more research into
what can be digitalised has been performed.
A few projects have been performed in the area virtual commissioning of PLC by,
mostly using specialised simulation softwares such as Process Simulate (by Siemens
PLM), Robot Studio (by ABB Robotics) or even CATIA/DELMIA (by Dassault
Systèmes) [14, 15, 16].
There has also been some studies on what should be the focus in the future [17].
They conclude that virtual commissioining is an important aspect in the future of
production development, but that it still has some obstacles to overcome, such as
deciding which accuracy level to strive for.
The idea of creating a Simulation model based on existing PLC code has been
examined for a few years [18, 19] but those models were never meant to be used for
anything other than to evaluate the PLC program.
However, the topic of this report will focus on the opposite, namely creating PLC
code based on a simulation model. Some research on automatic code generation
has already been done, with [20, 21, 22, 23, 24] focusing on creating PLC code in
several of the different languages described in section 2.3.1, although none of them
have examined how DES programs could be used in such applications.

9



3
Methods

3.1 Connecting Plant Simulation and PLCSIM
Advanced

Connecting Plant Simulation to a PLC is something that has been examined before,
with a master thesis by Viktor Engström and Zhizhong Liao investigating how a
connection via an OPC server works, as well as which limitations there are[10] .
However, from Plant Simulation 14.0 and onwards users have the possibility of con-
necting directly to PLCSIM Advanced. What follows here is a brief explanation of
the connection between Plant Simulation and PLCSIM_Advanced. A more com-
prehensive guide on the connection can be found in appendix B.

3.1.1 Creating the connection

In order to control the Plant Simulation model a connection to the virtual PLC
must be made. This is achieved by inserting a PLCSIM_Advanced object into the
model, whose dialog window can be seen in figure 3.1. The connection is created by
first inputting the name of the virtual PLC into the text box marked "name" and
then checking the "Active" box. A green dot will appear on the PLCSIM_Advanced
object when the connection is active. Pressing the button "Import Items..." when
the connection is active creates a table containing all signals and tags in the PLC
program. The signals are grouped into four categories which can be seen in table
3.1 [25].
The signals in the item lists can be connected to attributes and methods in Plant
Simulation by adding their path to the "Simulation Model Attribute" field at the
respective row.

Table 3.1: The four categories of signals that can be imported to Plant Simulation

I Input signals to the PLC Write access in Plant Simulation
O Output signals from the PLC Read access in Plant Simulation
M Marker Variables in the virtual PLC Read/write access in Plant Simula-

tion
DB Data in PLC data blocks Read/write access in Plant Simula-

tion

10



3. Methods

Figure 3.1: The dialog window of the PLCSIM_Advanced object in Plant Simu-
lation

3.1.2 Sending data
Data is exchanged between Plant Simulation and the PLC at set intervals. This
intevral can be adjusted by changing the "data exchnage interval" in the PLC-
SIM_Advanced object (see figure 3.1). A low number means that the data is ex-
changed more often, while a higher number exchanges data less frequently.
It is also possible to have a slower update rate on certain signal groups by changing
the interval field in the item list. If an interval in the item list is higher than the data
exchange rate then that group will update less frequently than the other signals. If
the interval value is lower than the data exchange value (including interval = 0)
however, the group should instead use the data exchange interval. Unfortunately,
this last feature doesn’t seem to work as intended in Plant Simulation 14.0. The
interval for the item groups will always override the data exchange interval, making
it redundant.
The PLC can receive the signals from the Plant Simulation model in different ways.
A signal can for example be connected to an attribute in the simulation. In fig-
ure 3.2 the IN-signal "PlantSimToggleButton" is directly connected to the value of
the checkbox (the button labelled "Start/Stop Conveyor"). When the value of the
checkbox changes, the IN-signals changes with it.
OUT-signals from the PLC can be connected to the Plant Simulation model in the
same way as IN-signals can. They can be directly linked to variables or attributes
via the Simulation Model Attribute field in the item list.

11



3. Methods

Figure 3.2: A table showing all IN-signals to the PLC as well as their aliases and
connected model attributes

A difference between IN and OUT signals is that OUT signals can be connected
directly to a SIMTALK method. When such an OUT-signal changes value the
method is triggered with the signal value as a parameter.

Notes regarding the data exchange

One very important thing to note is that the data exchange is not treated as an
event in Plant Simulation! This holds true for both signals sent to and from the
PLC. If the exchange should happen at a time when no events or activities are
executing in the simulation no data will be transferred. However, it would seem like
the exchange is "put on-hold" until the next event or activity happens in the model.

3.1.3 Building the test model
In order to test and understand how the connection between Plant Simulation and
PLCSIM_Advanced works a simple test model was created. The model can be seen
in figure 3.3, and the PLC code for the control system can be seen in appendix
C. The model contains a source connected to a buffer, which is connected to a
short line (with a sensor) that in turn is connected to the drain. It also contains
a PLCSIM_Advanced object that allows for direct communication with a virtual
PLC.

12



3. Methods

Figure 3.3: 3D view of the model used to test the connection with PLCSIM
Advanced. The Connection is set up with the PLCSIM object on the left of the line

The logic of the model is rather simple: The button labelled "Start/Stop Conveyor"
is connected to the tag "PlantSimToggleButton" in the PLC. When the value of the
button changes the connected PLC tag changes with it, which in turn changes
the value of the tag "ConveyorCTRL". This tag is connected to the attribute
Line.Stopped, which decides if the line is moving or not. The sensor on the line
sends a signal to the PLC each time a MU passes. This signal triggers a counter
that then sums up how many MU:s that have passed the sensor. The sensor also
triggers an internal counter that is used to compare the PLC logic to the internal
logic.

3.2 Coding with a standard
Before starting the modelling of the EMS line it was decided to use a shared standard
between Plant Simulation and the PLC, for a few key reasons:

• Easier to compare data in Plant Simulation and the PLC
• A Standard makes the system much more scaleable
• Easier communication between programmer and modeller

The next question was weather to use Volvo’s standard or to create a custom stan-
dard. Both ways have their own benefits and drawbacks, as seen in figure 3.2
In the end it was decided to use a custom standard as it allowed for a greater degree
of flexibility. The standard was to be based on Volvo’s standard for EMS lines [12]
with objects and signals sharing the same name in both Plant Simulation and the
PLC.

13



3. Methods

Table 3.2: Benefits and drawbacks of using different standards

Pros Cons
Volvo’s standard Accurately represents the real

system, pre-built library
Very complex, lots of su-
perfluous functions (alarms,
HMI:s)

Custom standard Tailor made for our needs,
Still based on Volvo standard,
easy to adapt

Unusable outside of the
project, extra work is needed
to create the library

3.2.1 Plant Simulation standard
The Plant simulation model contains a user-created toolbox, figure 3.4, that contains
an object for each different type of rail described by the Volvo Cars standard for
EMS lines [12]. Each of these objects contain methods and attributes that are used
when communicating with the PLC. Having these different types also allows for
easier changes to specific types of rails, as every rail of a certain type present in
the model are instances of the "blueprint" in the toolbox. Updating the "blueprint"
means that all rails of that class will immediately inherit the same changes.

Figure 3.4: A Plant Simulation Toolbox with nine different types of rail

The rails follow a naming standard of "T_Zone_Type+instance", with the T signi-
fying that the object is a type of track. Based on this standard it can easily be
understood that the rail with the name T_420_ACC1 is then the first ACC rail in
safety zone 420. The postscript _direction is added when a zone contains more
than one in- or outgoing track. Postscript _1 means that the track travels straight
after a switch or into a junction, while the postscript _9 is used for rails that enters
or leaves from the side. So a rail with the name T_330_ASB3_3 is the third ASB rail
in safety zone 330 and it turns after a switch.

3.2.2 PLC standard
The PLC contains a similar library as Plant Simulation with a function block (FB)
for each type of rail, as seen in figure 3.5, which can be dragged and dropped into
the PLC code. All rail function blocks follows the same I/O structure with the same
type of input and output signals, shown in figure 3.6.
The meaning and function of the I/O is listed in table 3.3:
The unique behaviour of each function block listed in the library is explained further
in appendix F.

14



3. Methods

Figure 3.5: The function block library in the PLC

Figure 3.6: An example of a rail control Function Block, showing the blocks inputs
to the left of the block, and outputs on the right side of the block.

When a new rail object is added to the Plant Simulation model, an instance of
the corresponding type to the Plant Simulation object should be inserted to a new
network in the PLC. The simulation object T_330_ASB3_3 is then controlled by an
ASB function block, connected to the data block DB_330_ASB3_3.
The naming of the blocks follow the same standard as the names in Plant Simulation,
with the exception of the T prefix. This makes it easy to see which block is connected
to which track, as block 330_TZ1 in the PLC has a sibling T_330_TZ1 in the Plant
Simulation model. The PLC I/O also follows the same standard meaning that the
signals for block 330_TZ2 all have "330_TZ2" as a prefix. This in turn means that
the only difference between the network 330_TZ2 and 330_TZ3 is the prefix of the
signals and the data block as seen in figure 3.7.

15



3. Methods

Table 3.3: The function of the rail control Function Blocks I/O signals

I/O Function
I_Blocked Blocking signal from the upstream rail. If high, stops all hangers

on the current rail to avoid collisions.
I_Occupied Input from the presence rail to the PLC that a hanger is currently

somewhere on the rail cut.
O_Power Enables power on the rail, allowing the hangers to travel.
O_SpeedCmd Sets a speed command in the form of an integer to all hangers

present on the rail.
O_Blocking Sends a blocking signal to the downstream rail if the current rail

is occupied.

Figure 3.7: A graphical representation of the differences between two instances of
the same rail type.

3.2.3 PLC hierarchy
The PLC program is built in layers in order to make it as scalable as possible. The
topmost layer is the "Main" block which controls the system by communicating with
the second layer. This layer is composed of the different safety zones explained in
section 2.5.1, with each zone represented by a separate block. These blocks, in turn,
contain instances of the blocks representing the different types of rails found in the
zone. This hierarchy is graphically explained in figure 3.8. Signals from the PLC
are only set in the lowest layer of the hierarchy.

3.3 Modelling the EMS
The modelling of the line in Plant Simulation started by creating the layout of the
EMS using regular line object. The measurements of the EMS line were taken from
the CAD files of the site.
The line objects making up the EMS were then systematically replaced with the ap-
propriate pieces from the user-created toolbox (figure 3.4) with the names following
the standard set in section 3.2.1. The sequence of rails were given by a chart over the
busses connected to the EMS, which did not contain any measurements. Therefore
the total length of the EMS remains correct, while the individual rail segments are
inaccurate. This problem is further explained in section 4.2.1.

16



3. Methods

Figure 3.8: A graphical representation of the hierarchy of the PLC program. The
main block can not communicate directly with the function blocks. However, blocks
on the same level depend on information from each other.

After two safety zones (320 and 330) were done in both the model and the PLC
code the model was test-run with the PLC. In order to make sure that model and
the PLC had the same signals an Excel spreadsheet was created that contained the
correct signal names for both applications. The spreadsheet could then be imported
into the TIA Portal or the item lists in the PLCSIM_Advanced object.
After modelling and testing another safety zone it was decided to investigate if
the PLC code could in some way be automatically generated based on the Plant
Simulation model, as described in section 3.4.
The rest of the model was constructed as before, while the PLC code were auto-
generated zone by zone as they were completed. A part of the completed model can
be seen in figure 3.9.

Figure 3.9: 2D view of a part of the Pant Simulation Model. The coloured back-
grouds represents different safety zones

17



3. Methods

3.4 Auto-generation of PLC code
As the PLC ladder code for every safety zone follows the same structure there is a
lot of repetitive code, and a lot of it can be copy-pasted. However if copy-pasting is
used, the order of the rails still differs from zone to zone, and needs to be rearranged
in the new code. Also, I/O signals still has to be rewritten and new data blocks for
every new rail function block needs to be created. This is an error prone process,
as it is easy to misspell an I/O variable, especially as they only differs to each other
with an integer. It was found that using a script to create the PLC connections
would be a quicker and safer process. However such a script is lacking in the TIA
Portal, PLC code was exported to XML and edited using a C# Program.
In order to automatically generate usable PLC code four steps had to be taken:

1. Create XML templates for the PLC blocks

A template for every type of rail, along with a matching data block, was first created
by hand in the TIA Portal, an example can be seen in figure 3.10. These are identical
to functional code but have their names and variables changed to generic ones that
can be found and replaced by a macro. The templates was then exported to XML
format using the TIAPortalOpennessDemo application introduced in section 2.3.4.
The XML code can be seen in appendix E.

Figure 3.10: The PLC template for an ACC network with generic signals and
variables at the connections instead of instance specific ones.

18



3. Methods

2. Create relevant data-set in Plant Simulation

Since the code is supposed to be generated based on the Plant Simulation model,
relevant data had to be extracted. The code shown in appendix D was used to create
a text file for each safety zone containing the name of all rails in reverse sequential
order (since that is how the PLC program is built). Since the PLC code and Plant
Simulation uses the same naming standard, this is all information that is needed to
map all variables and I/O for the rail control logic.

3. Create a program to edit the PLC templates

A C# program referred to as PLCBuilder was written that creates PLC or updates
PLC code for a safety zone with rail data from the zone exported directly from the
DES model in Plant Simulation.

4. Autogenerate PLC code with PLCBuilder

The first step to autogenerate PLC code for a safety zone is to first check if there
already exists PLC code for the zone in the TIA Portal. If it does, the code should
be exported to XML format using TIAPortalOpennessDemo to the directory of
PLCBuilder. Next step is to update the rail list input file to PLCBuilder. Then
when PLCBuilder is executed, it reads the rail list, and checks if the rail already
exists in the XML file for the existing PLC code. If not, it appends the XML
template of the listed rail type as seen figure 3.11, and renames the generic variables
according to the name in the list. An XML file for a Data block corresponding
to the Function Block generated is also created. If a rail object exists in the old

Figure 3.11: A text-file a list of all rails in safety zone 340, and a list of all XML
templates used for autogenerating a new PLC code.

PLC code but not in the list, it will delete the entire XML node for the rail cut.
When PLCBuilder has gone through the entire list and checked that it matches
with the XML file, the program is finished. The new autogenerated XML file can
then be imported into the PLC program and converted to functional ladder code
through TIAPortalOpennessDemo and then downloaded to the virtual PLC through
the TIA Portal. Examples of XML code and the result of the import can be found
in appendix E.

19



4
Results

Some problems were found stemming both from limitations in the software and from
the early state of some the functions being used. The software needs to mature
before the work method proposed by this project can prove beneficial for industry.
However, the connection between Plant Simulation and PLCSIM Advanced still
works despite these problems and it was possible to control the whole line.

4.1 Hardware differences between PLC:s
A problem can occur when using Plant Simulation as a virtual commissioning tool
for existing production lines, or when using pre-existing PLC-libraries. As explained
in section 2.3.3, PLCSIM Advanced can only emulate PLC:s with 1500- and 200SP
series CPU:s. If the library exists on an older hardware, e.g. a 300 series CPU,
there is a risk that parts of the library will be unusable, as functions might have
been dropped or changed.

4.2 Lack of detail in Plant Simulation
The types of objects that can be modelled in Plant Simulation can be rather limited,
especially compared to more specialised virtual commissioning tools such as Process
Simulate. The problem was also observed by [10] who claimed that not all objects
found in a production cell could be accurately represented. However, this should
prove to be a minimal problem as long as the Plant Simulation model focuses on
systems at line-level or higher.

4.2.1 Measurement problems in EMS
A problem more specific to the Plant Simulation model created during the project
is that the measurements of the rails are assumed. A blueprint of the EMS line were
provided by Volvo, which gave the overall lengths of the line. However, no blueprint
could be found giving the lengths of individual rail cuts. This means that the total
length of a piece of track is known, but not where the physical cuts are located.
This could prove troublesome as the model is no longer an accurate representation
of the real system, especially when times are important. But as this model is made
to test the connection between Plant Simulation and the PLC it did not affect the
result in any significant way.

20



4. Results

4.3 Slowdowns when running Plant Simulation
with a virtual PLC

One apparent problem were found while running the EMS line with a virtual PLC:
more signals resulted in a slower simulation speed. More signals means that the
simulation model has to handle more data during cycles since Plant Simulation ex-
changes data with the PLC at set intervals. The phenomenon is explained in greater
detail in section B.3.
The problems with the slowdowns can temporarily be solved by either increasing the
time-scaling factor up the virtual PLC or by changing the data exchange frequency
so that Plant Simulation updates less frequently. Of the two options the first one is
preferable, even though none of them are optimal.
Speeding up the PLC means that the data exchange is completed quicker. This also
means that the model can be simulated faster than real-time. However, if the PLC
is scaled faster or slower then the model it means that the PLC doesn’t work in the
same way as it would in a physical environment which invalidates the idea behind
virtual commissioning.
Reducing the update frequency of the signals poses the same risk of misrepresenting
the real system as time-scaling the PLC. Moreover there is a risk that important
signals are either missed or sent to the PLC too late. This can pose a problem
when sending pulses or alarm signals. There also exist a problem wherein the up-
date interval of the item groups always override the data exchange interval of the
PLCSIM_Advanced object. This problem is further explained in appendix B.3.

4.4 Connection between Plant Simulation and
TIA Portal

There are currently no way of connecting or transferring data between Plant Sim-
ulation and the TIA Portal. The methods used in this project has either been to
transfer the signal list via Excel or by using TIAPortalOpennessDemo and the C#
program presented in section 3.4.

4.5 Creating the PLC code
It was quickly discovered during the modelling of the EMS line that the creation
of the PLC code often led to errors, mostly in the form of spelling mistakes or
miscouplings in the PLC code. Some of the problems stemmed from bad commu-
nication between the modeller and the programmer, while some problems stemmed
from the homogeneous nature of the standard, e.g. misreading and working on block
T_330_SB2_9 instead of T_330_SB1_9. In this case copy-pasting code sections are
one way of reducing the amount of repetitive coding but this further increases the
chance of mislabelling variables signals in the code.

21



4. Results

Another oblivious problem is that the time needed for writing the code increases as
the model grows and the function blocks becomes more complex. This also leads
to a greater chance of errors or forgotten signals. The solution to these problems is
to auto generate the PLC code based on the previously made code and information
from the Plant Simulation model. The details is explained earlier in section 3.4.

4.6 Lack of documentation
Finally, one of the problems found is the absence of documentation regarding the
communication between Plant Simulation to PLCSIM Advanced. Much of the infor-
mation on how the connection works are either wrong, (such as how a signal groups
should choose the higher of the group interval or the exchange interval while they
in reality always chooses the group specific) or missing (such as the data exchange
not being classified as an event in Plant Simulation). The lack of documentation
also means that it’s hard to fix problems such as the error in figure 4.1, as it doesn’t
explain where or why the problem occurs.

Figure 4.1: An error prompt in Plant Simulation. There are no available docu-
mentation on why this error occurs or how to fix the problem.

22



5
Conclusion

All in all it can safely be said that Plant Simulation can be used as a tool for
virtual commissioning of PLC code, but the software’s needs to be updated and
engineered for the new tasks first. What follows is a summary of the parts that
needs to be improved and what kind of knowledge that is needed for this type of
work. The research questions introduced in section 1.4 will be discussed in the
following sections. The questions RQ1 through RQ3 will be discussed in sections
5.2 through 5.4 respectively.

5.1 Improvement potential in the software

The project has shown that Plant simulation can be used as a tool for virtual
commissioning, at least in small to medium sized projects. There are however a few
aspects that have to be improved or further investigated before this can be adapted
into the engineers toolbox:

• The problem with the data exchange interval explained in sections 4.3 and
B.3 has to be fixed.

• Pressing the "import item" button should update the existing item groups
rather than creating new groups.

– The problem with creating new groups is that the simulation model at-
tribute doesn’t carry over between from the old groups with the same
name, so they will have to be added again.

• It should be possible to share, or at least connect, libraries in Plant Simulation
and the TIA Portal.

– When adding an object into the Plant Simulation model it should be as
easy as possible to add the respective function block to the PLC.

• It should be possible to create and connect variables and I/Os to function
blocks using macros within the TIA Portal.

– The current method of using TIAPortalOpennessDemo also requires un-
derstanding of both XML and another programming environment (such
as C#) to create an application that auto generates new PLC code.

23



5. Conclusion

5.2 Limitations of the connection between Plant
Simulation and PLC

In the current state the modeller and/or programmer must posses certain skills in
order to do utilise Plant Simulation in the context of PLC design:

• Knowledge about the system

– The discrete event model should be modelled as accurately as possible to
the real system, which means that the modeller needs to have access to
blueprints and measurements

• Knowledge about Discrete event simulation

– The modeller must understand how to create a functioning DES model,
as well as how to emulate objects in the real system not available in the
DES software

• Knowledge about PLC programming

– The Programmer needs knowledge about PLC programming to write the
code that runs the simulation model. Even if an auto-generated approach
is chosen such as the one in this project, an understanding of PLC pro-
gramming is necessary to design the structure and the templates to be
used by the PLC code generator.

• Knowledge about other programming

– Writing the I/O list is too time consuming in both Plant Simulation and
the PLC for larger projects and writing a macro that auto-generates the
I/O list becomes almost necessary. Writing an application that generates
PLC code in XML format is both requires understanding of XML code
and a programming environment able to edit XML files, such as C#.

5.3 The extent to which PLC code can be
designed based on a Plant Simulation model

• It is possible to generate a functional draft of PLC code for an EMS line to be
used for further development by using the method explained in this project.

– similarly, higher level of industrial robot control should easily be pro-
grammed using the same method, with only consideration to start and
end positions and zone booking e.g. no kinematics or collision detection.

• The level of detail of Plant Simulation is insufficient to model detailed station
behaviour and hence the method is only suitable for higher level of control of
production systems.

24



5. Conclusion

5.4 Future research topics
One of the major drawbacks of using the method proposed in this report is that the
Plant Simulation user has to do double work. There is currently no possible way
of translating SIMTALK into ladder or vice versa. This means that two different
models will be built, one for each way of control. A proposal for future research
would be to either create a macro that can switch a model from using any of the
two languages. Another similar topic would be to evaluate whereat or not a Plant
Simulation model can be coded using ladder logic.
Another drawback of controlling a DES model with a PLC is that you can’t simulate
very quickly. The maximum possible speed achieved with PLCSIM Advanced is a
time scaling factor of 100. This relatively slow reading speed makes such a model
unfit for "regular" simulation uses such as capacity analysis, as simulating a multiple
runs of full years of productions is not uncommon to achieve a higher precision.
Even shorter experiments would take an unreasonable long time to complete. Future
research could focus on creating virtual PLC:s that can achieve much higher reading
speeds.
Another future application would be to connect Plant Simulation directly to the
TIA Portal. The two programs should share a library, so that when an object is
inserted into Plant Simulation a corresponding block is inserted into a network in
the TIA Portal.

5.5 Closing statements
The project has shown that Plant Simulation can be used for PLC design in the
future, but it still requires a lot of polish. Furthermore, Plant Simulation should
focus more on testing the flow control of larger systems with a low-complexity control
system while real-time simulation software such as Process Simulate are better suited
for smaller or more signal-heavy applications.

25



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2F978-1-4757-3552-9.pdf.

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https://doi.org/10.1111/1467-9884.00369{\_}9
https://doi.org/10.1111/1467-9884.00369{\_}9
https://link.springer.com/content/pdf/10.1007%2F978-1-4757-3552-9.pdf
https://link.springer.com/content/pdf/10.1007%2F978-1-4757-3552-9.pdf
https://doi.org/10.1007/s13398-014-0173-7.2
http://arxiv.org/abs/9809069v1
http://arxiv.org/abs/9809069v1
https://www.informs-sim.org/wsc08papers/005.pdf%20http://portal.acm.org/citation.cfm?id=256563.256571
https://www.informs-sim.org/wsc08papers/005.pdf%20http://portal.acm.org/citation.cfm?id=256563.256571
https://doi.org/10.1007/978-3-319-19503-2{\_}1
https://doi.org/10.1007/978-3-319-19503-2{\_}1
http://link.springer.com/10.1007/978-3-319-19503-2_1
http://link.springer.com/10.1007/978-3-319-19503-2_1
https://doi.org/10.1016/j.rser.2016.01.025
https://doi.org/10.1016/j.rser.2016.01.025
https://ac.els-cdn.com/S1364032116000551/1-s2.0-S1364032116000551-main.pdf?_tid=746c97bd-f699-4fdb-9371-bcca2552ef1f&acdnat=1526627328_6acc9fdce366942564d73cf26dcf0bd7
https://ac.els-cdn.com/S1364032116000551/1-s2.0-S1364032116000551-main.pdf?_tid=746c97bd-f699-4fdb-9371-bcca2552ef1f&acdnat=1526627328_6acc9fdce366942564d73cf26dcf0bd7
https://ac.els-cdn.com/S1364032116000551/1-s2.0-S1364032116000551-main.pdf?_tid=746c97bd-f699-4fdb-9371-bcca2552ef1f&acdnat=1526627328_6acc9fdce366942564d73cf26dcf0bd7
https://doi.org/10.1016/B978-0-12-802929-9.00001-7
https://ac.els-cdn.com/B9780128029299000017/3-s2.0-B9780128029299000017-main.pdf?_tid=0cd4a36e-02d9-4d6c-a4b5-b24e5033327e&acdnat=1526627192_13d095ba4ac834cfe56ea2b9e7218f52
https://ac.els-cdn.com/B9780128029299000017/3-s2.0-B9780128029299000017-main.pdf?_tid=0cd4a36e-02d9-4d6c-a4b5-b24e5033327e&acdnat=1526627192_13d095ba4ac834cfe56ea2b9e7218f52
https://ac.els-cdn.com/B9780128029299000017/3-s2.0-B9780128029299000017-main.pdf?_tid=0cd4a36e-02d9-4d6c-a4b5-b24e5033327e&acdnat=1526627192_13d095ba4ac834cfe56ea2b9e7218f52
https://ac.els-cdn.com/B9780128029299000017/3-s2.0-B9780128029299000017-main.pdf?_tid=0cd4a36e-02d9-4d6c-a4b5-b24e5033327e&acdnat=1526627192_13d095ba4ac834cfe56ea2b9e7218f52
http://www.plcopen.org/pages/tc1_standards/iec_61131_3/
http://www.plcopen.org/pages/tc1_standards/iec_61131_3/
https://support.industry.siemens.com/cs/document/108716692/tia-portal-openness%3A-introduction-and-demo-application?dti=0&lc=en-WW
https://support.industry.siemens.com/cs/document/108716692/tia-portal-openness%3A-introduction-and-demo-application?dti=0&lc=en-WW
https://support.industry.siemens.com/cs/document/108716692/tia-portal-openness%3A-introduction-and-demo-application?dti=0&lc=en-WW
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A
Connecting PLCSIM Advanced to

the TIA Portal

A.1 Setting up the Virtual PLC
For running PLCSIM Advanced Instance and the PlantSimulation model on differ-
ent Host and client PCs you must first select PLCSIM Virtual Eth. Adapter in
the Online Access settings. TCP/IP Communication should be set to Local Area
Connection as in figure A.1.

Figure A.1: The PLCSIM Advanced Interface for Online Access and TCP/IP
communication.

In the Start PLC tab a unique instance name should be assigned for each virtual
PLC instance. If an existing Instance name is chosen, the virtual PLC will load
the old PLC:s files from the Virtual SIMATIC Memory Card. The IP address
should preferably be set to IP address 192.168.1.1 as the virtual PLC instance will
automatically be reset to the IP address 192.168.0.1 when the TIA portal connects
to the virtual controller. The sub-net mask should be set to 255.255.255.0. as shown
in figure A.2.

Figure A.2: The Start tab in PLCSIM Advanced showing the an example of
instance name and the correct IP address and Sub-net mask.

I



A. Connecting PLCSIM Advanced to the TIA Portal

A.1.1 Using the Virtual Ethernet Adapter
The Runtime manager port is used to identify the PLC from the client and should
be set to port 50000 and enabled with the tick box next to it as in figureA.3.

Figure A.3: The PLCSIM Advanced Interface.

Checking the runtime manager port starts the Siemens PLCSIM Virtual Ethernet
Adapter and installs Siemens PLCSIM Virtual switch program to the the Ethernet
adapter of the host PC. The Virtual Switch enables data exchange between the
physical and virtual Ethernet adapters. After the installation, the a new Local
Area Connection should show up for the Virtual Ethernet Adapter in the Network
Connections folder in the Windows Control Panel, and the Virtual Switch should
show up under the used items list in the physical Ethernet adapters properties as in
figure A.4.

A.2 Configuring TIA for simulation
Check Support simulation during block compilation must be enabled in the Protec-
tion tab in the projects properties menu as in figure A.5 and A.6. This is compiles
the PLC code in a format that is able to be downloaded and run on the virtual PLC.

A.3 Connecting and downloading to the virtual
PLC

First scan for devices according to A.7 or pressing download to device. Then in
Extended download to device window follow the following steps:

1. Select Siemens PLCSIM Virtual Ethernet Adapter in PG/PC Interface if it’s
not automatically selected.

2. connection to interface/subnet: try all interfaces
3. Press Start Search
4. select the device at address 192.168.1.1 with the same name as the projects

PLC, not the one with the .profinet interface extension to the name in the list
of target device

5. press Load in the extended download to device window.
6. Press yes in a command promt asking the user to assign a additional IP Ad-

dress.

II



A. Connecting PLCSIM Advanced to the TIA Portal

Figure A.4: Showing the Siemens PLCSIM Virtual switch protocol installed on the
physical Ethernet adapter Inter(R) Ethernet Connection and the Siemens PLCSIM
Virtual Ethernet Adapter in the Network Connections list in the Windows Control
Panel.

7. An IP Address on the same subnet as the device is added.
8. Press extebded download to device again.
9. Select and load to the device at address 192.168.1.1.
10. the Download Preview window opens.
11. Press Load in the Download Preview window
12. Press finish when the PLC is fully loaded and the program is successfully

loaded to the virtual PLC.

A.4 Converting 300 code to 1500
issue with converting the existing library to the virtual PLC due to different variants
most of the code can be converted but standard function blocks in one PLC demand
different inputs and outputs than the same FB in the other PLC
several function blocks from the old library was unusable after they had all been
imported and had to be imported again, after which point they worked.

III



A. Connecting PLCSIM Advanced to the TIA Portal

Figure A.5: Showing where to find the project properties menu.

Figure A.6: Showing where to check Support simulating during block compilation
in the project properties menu.

IV



A. Connecting PLCSIM Advanced to the TIA Portal

Figure A.7: Showing how to search for devices in the TIA Portal.

Figure A.8: Showing the Extended donwload to device window in the TIA Portal.

V



B
Connecting Plant Simulation to a

virtual PLC

B.1 Setting up the connection
When connecting a virtual PLC to Plant Simulation some preparations have to be
made. First of all you must make sure that the PLCSIM_Advanced package is
included in the model. This is achieved by pressing the button named "Manage
Class Library" under the "Home" ribbon. In the "Basic Objects" tab , scroll down
to the line with PLCSIM_Advanced and tick the checkbox, as shown in figure B.1.

Figure B.1: The Manage Class Library screen. Activated objects have a ticked
checkbox

After clicking the OK button the object should appear in the toolbox under the
"Information Flow" tab, like in figure B.2.

VI



B. Connecting Plant Simulation to a virtual PLC

Figure B.2: The toolbar in Plant Simulation with the PLCSIM_Advanced object
selected

The PLCSIM_Advanced object is then inserted into the model in the same way
as any other entity. The connection to a local virtual PLC is made by opening
the PLCSIM_Advanced block and inserting the name of the virtual PLC into the
field named "Instance Name" and then ticking the box named "Active". A green
dot on the PLCSIM_Advanced object shows that the connection is active. Figure
B.3 shows how the connection is made. Refer to section B.2 for a guide on how to
connect Plant Simulation to a virtual PLC on a remote desktop.

Figure B.3: Figure showing how to connect the PLCSIM_Advanced object to the
virtual PLC

Once a connection is established Plant Simulation can begin to process signals to
and from the PLC. However, in order for the PLC to be able to affect the simulation
the signals must be connected to attributes in the model. This can be achieved in
two different ways. Pressing the "Import Items..." button in the PLCSIM_Advanced
object simply imports all of the tags found in the PLC, grouped into four different
categories (see table 3.1).
Signals can also be added manually by first clicking on the "Items" button and then
selecting (or creating) a signal group. Furthermore, you can also import signals from
spreadsheets created in external programs such as Excel.

VII



B. Connecting Plant Simulation to a virtual PLC

Double clicking on any of the four categories brings up a list of all the signals of that
type. The "Identifier" column shows the name of the signal in the PLC, while the
"Alias" column shows the path to the signal. In figure B.4 the path to the PLC tag
"SensorSignalFromPlantSim" is .Models.Frame.PLC.SensorSig. The Simulation
Model Attribute field can be filled in to connect the signal directly to a specific
attribute, variable or SIMTALK method in Plant Simulation.

Figure B.4: A table showing all IN-signals to the PLC as well as their aliases and
connected model attributes

B.1.1 Sending data to the PLC
The PLC can receive signals from the Plant Simulation model in different ways.
A signal can for example be connected to an attribute in the simulation. In fig-
ure B.4 the IN-signal "PlantSimToggleButton" is directly connected to the value of
the checkbox (the button labelled "Start/Stop Conveyor"). When the value of the
checkbox changes, the IN-signals changes with it.
An IN-signal can also be set directly from a SIMTALK method as if it was a regular
variable in Plant Simulation. This also means that the signal can only change value
when the method is triggered (unless it is also connected to a model attribute). The
code in listing B.1 shows a way to send a pulse to the PLC when a sensor is triggered.
A method has to be used for this since it’s currently not possible to connect an IN
signal directly to a sensor. This is because sensors are not defined objects in Plant
Simulation. Sensors are instead treated as internal methods in the objects on which
they are located, and methods cannot be connected to PLC IN-signals.

1 //Plant Simulation code for sending a pulse
2 --Start method when sensor is triggered
3 param SensorID: integer, Front: boolean
4 --Send TRUE
5 PLC.sensorSig := True
6 --Wait slightly longer than update frequency

VIII



B. Connecting Plant Simulation to a virtual PLC

7 wait 0.05
8 --Send FALSE
9 PLC.sensorSig := False

Listing B.1: Example of how a pulse can be sent

If a sensor is supposed to send a high signal while triggered, as opposed to a pulse,
it can be solved by setting the sensor to trigger on both back and front while using
a method similar to that in listing B.2:

1 //Method to hold signal value
2 --Parameter "Front" is true when MU enters sensor range and false when MU

exits sensor range
3 param SensorID: integer, Front: boolean
4 --Set the signal to the PLC to the value of parameter "Front"
5 PLC.sensorSig := Front

Listing B.2: Example of how a signal can be high while a MU passes

B.1.2 Receiving data from the PLC
OUT-signals from the PLC can also be connected to the Plant Simulation model
in the same way as IN-signals can. They can be directly linked to variables or
attributes via the Simulation Model Attribute field in the item list.
A difference between IN and OUT signals is that OUT signals can be connected
directly to a SIMTALK method, as seen in figure B.5. When such an OUT-signal
changes value the method is triggered with the signal value as a parameter (see
listing B.3). The signal must be declared as a parameter in the method, but the
parameter does not have to be used.

Figure B.5: Two OUT-signals connected to a method and a global variable re-
spectively

IX



B. Connecting Plant Simulation to a virtual PLC

1 //Method LineCTRL
2 --Recieve PLC-signal as parameter
3 param LineActive : boolean
4 --Set the attribute "stopped" of the objcet "line" to the same value as

the incoming signal
5 line.stopped := LineActive

Listing B.3: The PLC-signal is sent to the method LineCTRL as the parameter
LineActive. The attribute stopped in the object line is then set to the same value
as the incoming PLC-signal

B.2 Connecting to a remote virtual PLC

Using a virtual PLC on a remote desktop works much in the same way as using it on a
local one, although a few extra steps have to be taken to make the connection. First
of all the two computers must be connected to the same network, either via LAN
or Ethernet cable. Secondly, the virtual PLC must be using the PLCSIM Virtual
Ethernet Adapter (refer to appendix A, section A.1.1 for how to do this).
Lastly you must add the address to the computer that is running the PLC, as
well as the port it connects through, in the field labelled "Remote runtime manager".
When that is done the connection is made by checking the "active" checkbox and
pressing the "Apply" or "OK" buttons in the dialog window.

Figure B.6: Figure showing how to input the address and port number when
connecting to a remote virtual PLC

X



B. Connecting Plant Simulation to a virtual PLC

B.3 Understanding the data exchange interval

In large models with many signals between Plant Simulation and the PLC perfor-
mance can become an issue. The problem stems from the fact that Plant Simulation
updates the signal lists at set intervals. However, the update rate (in milliseconds)
can be changed in the "Data exchange interval" field in the PLCSIM_Advanced ob-
ject (see figure B.7). A low number means that the data is exchanged more often,
while a higher number exchanges data less frequently.
A slight exception occurs if the data exchange interval is set to 0; In that case the
PLC is set to single step mode and data is exchanged after each cycle in the PLC.
Furthermore the PLC is set in freeze-mode during the data exchange to make sure
that all signals are transferred correctly. The freeze state is a specific mode in the
virtual PLC where the virtual time is stopped, no timers are running and the pro-
gram is not executed [7]. This is however NOT the same as stopping the PLC.

Figure B.7: Figure showing the data exchange interval fields in the PLC-
SIM_Advanced object and the item groups

It is also possible to have a slower update rate on certain signal groups by changing
the interval field in the item list (see figure B.7). If an interval in the item list
is higher than the data exchange rate then that group will update less frequently
than the other signals. If the interval value is lower than the data exchange value
(including interval = 0) however, the group should instead use the data exchange
interval. Unfortunately, this last feature doesn’t seem to work as intended in Plant
Simulation 14.0. The interval for the item groups will always override the data
exchange interval, making it redundant. Setting the data exchange interval to 2
seconds and a group interval to 20 milliseconds means that the group will exchange
data every 20 milliseconds.

XI



B. Connecting Plant Simulation to a virtual PLC

B.3.1 Notes regarding the data exchange
One very important thing to note is that the data exchange is not treated as an
event in Plant Simulation! This holds true for both signals sent to and from the
PLC. If the exchange should happen at a time when no events or activities are
executing in the simulation no data will be transferred. However, it would seem like
the exchange is "put on-hold" until the next event or activity happens in the model.

XII



C
Control logic of the test model

The following chapter further explains the control logic of the test model. Figure
C.1 shows the four networks making up the PLC code, figure C.2 shows how the
PLC-IN signals are connected in Plant Simulation while C.3 shows the PLC-OUT
signals.

XIII



C. Control logic of the test model

Figure C.1: The PLC code used for controlling the test model

XIV



C. Control logic of the test model

Figure C.2: The list of IN-signals and their connections in Plant Simulation

Figure C.3: The list of OUT-signals and their connections in Plant Simulation

XV



D
SIMTALK code for exporting data

Plant Simulation has many ways of sharing and exporting data that is interesting
and relevant to development projects. However, there is no way of exporting data
such as layouts or connections to external programs. A SIMTALK code was therefore
written so that information relevant to the PLC code generation could be exported
The code in listing D.1 is used to create a table, in reverse sequential order, of all
rails in a safety zone. The table can then exported as a text file, XML file or Excel
spreadsheet.

1 -- .Models.Frame.XMLUpdater
2 /***********************************************
3 This method is used to create a list of all tracks in a
4 safety zone in reverse sequential order.
5 Tracks that goes straight (postscript "_1") are added first
6 and deviating tracks (postscript "_1") are added afterwards.
7 The list is used in the C# programme to autogenerate PLC code
8 for the specific safety zone.
9 ************************************************/

10 param Zone : string -> table[string,string]
11
12 var FramePath : object := .models.frame
13 var ThisObject : object
14 var MemoryObject: object
15 var FirstPIB : object
16 var LastPIB : object
17 var FirstPIB2 : object
18 var LastPIB2 : object
19
20 var IsTrack : string := "T_"
21 var IsSwitch : string := "SW"
22 var IsStraight : string := "_1"
23 var IsDeviant : string := "_9"
24 var IsPIB : string := "PIB"
25
26 var BlockType : string
27 var FirstPIBName: string
28 var LastPIBName : string
29 var NameToEdit : string
30 var PrevZone : string
31 var SuccArray : string[]

XVI



D. SIMTALK code for exporting data

32 var PIBZone : string
33
34 var i : integer:= 1
35 var j : integer:= 1
36
37 var FirstPIBBool: boolean:= FALSE
38 var LastPIBBool : boolean:= FALSE
39 ------------------------------------------------
40
41 //This is the table that is returned to the calling method
42 result.create
43 //A new zone always starts after a PIB
44 FirstPIBName := Zone+"_"+IsPIB
45
46 //Loop to find the first PIB
47 //If more than one is found the zone has two incoming tracks
48 repeat
49 //Find the first PIB
50 if pos(FirstPIBName,FramePath.node(i).name) > 0 AND FirstPIBBool =

FALSE
51 FirstPIBBool := TRUE
52 FirstPIB := FramePath.node(i)
53 //Look for a second first PIB
54 elseif pos(FirstPIBName,FramePath.node(i).name) > 0 AND

FirstPIBBool = TRUE
55 FirstPIB2 := FramePath.node(i)
56 end
57 i := i + 1
58 until i = FramePath.numNodes
59
60 //Loop to find the last PIB
61 //If more than one is found the zone has two outgoing tracks
62 repeat
63 //Find the last PIB
64 if pos(Zone,FramePath.node(j).name) > 0 AND pos(IsPIB,FramePath.

node(j).name) > 0 AND pos(FirstPIBName,FramePath.node(j).name) = 0 AND
LastPIBBool = FALSE

65 LastPIB := FramePath.node(j)
66 LastPIBBool := TRUE
67 //Look for a second last PIB
68 elseif pos(Zone,FramePath.node(j).name) > 0 AND pos(IsPIB,

FramePath.node(j).name) > 0 AND pos(FirstPIBName,FramePath.node(j).
name) = 0 AND LastPIBBool = TRUE

69 LastPIB2 := FramePath.node(j)
70 end
71 j := j + 1
72 until j = FramePath.numNodes
73
74 //Add all straight tracks

XVII



D. SIMTALK code for exporting data

75 ThisObject := FirstPIB.succ(1)
76 repeat
77 if pos(IsTrack,ThisObject.name) > 0 AND pos(IsSwitch,ThisObject.

name) = 0 -- Only add Tracks
78 NameToEdit := ThisObject.name
79 BlockType := omit(NameToEdit,1,6) -- Remove the string "

T_XXX_"
80 //Add the track zone and type to the top of the list
81 result.InsertRow(1)
82 result.WriteRow(1,1,Zone)
83 result.WriteRow(2,1,BlockType)
84 elseif pos(IsSwitch,ThisObject.name) > 1 AND ThisObject.numSucc >

1--If switch, look for more successors
85 MemoryObject := ThisObject.succ(2) --This WILL be

overwritten i a safetyzone has more than one switch (by design)
86 end
87 ThisObject := ThisObject.Succ(1) --Go to next succesor
88 until ThisObject = LastPIB OR ThisObject = LastPIB2
89
90 --Add last PIB to result
91 SuccArray := splitString(ThisObject.succ(1).name,"_")
92 PIBZone := Zone+"_"+SuccArray[2]
93 result.InsertRow(1)
94 result.WriteRow(1,1,PIBZone)
95 result.WriteRow(2,1,IsPIB)
96
97 //If there are two incoming tracks, add the deviates
98 if FirstPIB2 /= void
99 ThisObject := FirstPIB2.succ(1)

100 repeat
101 NameToEdit := ThisObject.name
102 BlockType := omit(NameToEdit,1,6) -- Remove the string "

T_XXX_"
103 //Add the track zone and type to the top of the list
104 result.InsertRow(1)
105 result.WriteRow(1,1,Zone)
106 result.WriteRow(2,1,BlockType)
107 ThisObject := ThisObject.Succ(1)
108 until ThisObject.numPred > 1 -- When the next object has more than

one predecessor all deviates are added
109 end
110
111 //If there are two outgoing tracks, add the deviates
112 if MemoryObject /= void
113 ThisObject := MemoryObject
114 repeat
115 NameToEdit := ThisObject.name
116 BlockType := omit(NameToEdit,1,6) -- Remove the string "

T_XXX_"

XVIII



D. SIMTALK code for exporting data

117 //Add the track zone and type to the top of the list
118 result.InsertRow(1)
119 result.WriteRow(1,1,Zone)
120 result.WriteRow(2,1,BlockType)
121 ThisObject := ThisObject.Succ(1)
122 until ThisObject = LastPIB OR ThisObject = LastPIB2 -- When the

next object is a PIB, stop
123 //Find the name of the last PIB
124 SuccArray := splitString(ThisObject.succ(1).name,"_")
125 PIBZone := Zone+"_"+SuccArray[2]
126 //Add the PIB to the top of the list
127 result.InsertRow(1)
128 result.WriteRow(1,1,PIBZone)
129 result.WriteRow(2,1,IsPIB)
130 end
131
132 //Define the start of the safety zone
133 result.InsertRow(1)
134 result.WriteRow(1,1,Zone)
135 result.WriteRow(2,1,"START")
136
137 //Define the end of the safety zone
138 result.AppendRow("END","END")
139
140 return result

Listing D.1: The SIMTALK code used for creating the tables that are imported
into PLCBuilder

XIX



E
XML code for safety zone 320

TIAPortalOpenessDemo connects to the STEP 7 TIA Portal and allow the import
and export of ladder code as XML. C# Program PLCBuilder mentioned in 3.4
reads in an existing XML file if an update of a current code is desired, if a new auto
generated code the program instead reads in an XML template as in listing E.1.
The program appends a rail XML template at row 58 (under the text
INSERT_TEMPLATE_BELOW) for each rail cut listed in the list from Plant Simulation,
and generic variables in the template are updated with the data from Plant Simu-
lation. The XML file is then saved in the TIAPortalOpenness directory.
The XML code is imported into the PLC program in the TIA Portal via the TIA-
PortalOpennessDemo application. The application transforms the XML code into
ladder logic which can then be loaded into a PLC.

1 <?xml version="1.0" encoding="utf-8"?>
2 <Document>
3 <Engineering version="V15" />
4 <SW.Blocks.FC ID="0">
5 <AttributeList>
6 <AutoNumber>true</AutoNumber>
7 <CodeModifiedDate ReadOnly="true">2018-04-23T07:50:22.1699085Z</

CodeModifiedDate>
8 <CompileDate ReadOnly="true">2018-04-23T07:50:45.9334297Z</

CompileDate>
9 <CreationDate ReadOnly="true">2018-04-23T07:44:16.4882299Z</

CreationDate>
10 <HandleErrorsWithinBlock ReadOnly="true">false</

HandleErrorsWithinBlock>
11 <HeaderAuthor />
12 <HeaderFamily />
13 <HeaderName />
14 <HeaderVersion>0.1</HeaderVersion>
15 <Interface><Sections xmlns="http://www.siemens.com/automation/

Openness/SW/Interface/v3">
16 <Section Name="Input" />
17 <Section Name="Output" />
18 <Section Name="InOut" />
19 <Section Name="Temp">
20 <Member Name="tempblocked1" Datatype="Bool" />
21 </Section>
22 <Section Name="Constant" />

XX



E. XML code for safety zone 320

23 <Section Name="Return">
24 <Member Name="Ret_Val" Datatype="Void" Accessibility="Public" />
25 </Section>
26 </Sections></Interface>
27 <InterfaceModifiedDate ReadOnly="true">2018-04-23T07:44:16.4882299Z<

/InterfaceModifiedDate>
28 <IsConsistent ReadOnly="true">true</IsConsistent>
29 <IsIECCheckEnabled>false</IsIECCheckEnabled>
30 <IsKnowHowProtected ReadOnly="true">false</IsKnowHowProtected>
31 <IsWriteProtected ReadOnly="true">false</IsWriteProtected>
32 <LibraryConformanceStatus ReadOnly="true">Error: The block contains

calls of single instances.
33 Warning: The block contains direct access to inputs, outputs, bit memories

, indirect access to the registry or indirect access to external
memory areas that are unknown at the time of compilation.

34 </LibraryConformanceStatus>
35 <MemoryLayout>Optimized</MemoryLayout>
36 <ModifiedDate ReadOnly="true">2018-04-23T07:50:22.1699085Z</

ModifiedDate>
37 <Name>T_ACC</Name>
38 <Number>8</Number>
39 <ParameterModified ReadOnly="true">2018-04-23T07:44:16.4882299Z</

ParameterModified>
40 <PLCSimAdvancedSupport ReadOnly="true">true</PLCSimAdvancedSupport>
41 <ProgrammingLanguage>LAD</ProgrammingLanguage>
42 <SetENOAutomatically>False</SetENOAutomatically>
43 <StructureModified ReadOnly="true">2018-04-23T07:44:16.4882299Z</

StructureModified>
44 <UDABlockProperties />
45 <UDAEnableTagReadback>false</UDAEnableTagReadback>
46 </AttributeList>
47 <ObjectList>
48 <MultilingualText ID="1" CompositionName="Comment">
49 <ObjectList>
50 <MultilingualTextItem ID="2" CompositionName="Items">
51 <AttributeList>
52 <Culture>en-US</Culture>
53 <Text />
54 </AttributeList>
55 </MultilingualTextItem>
56 </ObjectList>
57 </MultilingualText>
58 INSERT_TEMPLATE_BELOW
59 INSERT_TEMPLATE_ABOVE
60 <MultilingualText ID="8" CompositionName="Title">
61 <ObjectList>
62 <MultilingualTextItem ID="9" CompositionName="Items">
63 <AttributeList>
64 <Culture>en-US</Culture>

XXI



E. XML code for safety zone 320

65 <Text />
66 </AttributeList>
67 </MultilingualTextItem>
68 </ObjectList>
69 </MultilingualText>
70 </ObjectList>
71 </SW.Blocks.FC>
72 </Document>

Listing E.1: The XML template for a safety zone to which rail templates are either
manually or using PLCBuilder.

E.1 Results from imported code

Importing the code found in listing E.2 produces the PLC code seen in figure E.1.

1 <Document>
2 <Engineering version="V15" />
3 <SW.Blocks.FC ID="0">
4 <AttributeList>
5 <AutoNumber>true</AutoNumber>
6 <CodeModifiedDate ReadOnly="true">2018-04-13T12:51:43.0092879Z</

CodeModifiedDate>
7 <CompileDate ReadOnly="true">2018-04-18T10:18:55.5744709Z</

CompileDate>
8 <CreationDate ReadOnly="true">2018-04-05T09:54:47.8320375Z</

CreationDate>
9 <HandleErrorsWithinBlock ReadOnly="true">false</

HandleErrorsWithinBlock>
10 <HeaderAuthor />
11 <HeaderFamily />
12 <HeaderName />
13 <HeaderVersion>0.1</HeaderVersion>
14 <Interface><Sections xmlns="http://www.siemens.com/automation/

Openness/SW/Interface/v3">
15 <Section Name="Input">
16 <Member Name="I_Blocked" Datatype="Bool" Accessibility="Public" />
17 </Section>
18 <Section Name="Output">
19 <Member Name="O_Occupied" Datatype="Bool" Accessibility="Public" />
20 </Section>
21 <Section Name="InOut" />
22 <Section Name="Temp" />
23 <Section Name="Constant" />
24 <Section Name="Return">
25 <Member Name="Ret_Val" Datatype="Void" Accessibility="Public" />
26 </Section>
27 </Sections></Interface>

XXII



E. XML code for safety zone 320

28 <InterfaceModifiedDate ReadOnly="true">2018-04-10T07:28:52.155191Z</
InterfaceModifiedDate>

29 <IsConsistent ReadOnly="true">true</IsConsistent>
30 <IsIECCheckEnabled>false</IsIECCheckEnabled>
31 <IsKnowHowProtected ReadOnly="true">false</IsKnowHowProtected>
32 <IsWriteProtected ReadOnly="true">false</IsWriteProtected>
33 <LibraryConformanceStatus ReadOnly="true">Error: The block contains

calls of single instances.
34 Warning: The object contains access to global data blocks.
35 Warning: The block contains direct access to inputs, outputs, bit memories

, indirect access to the registry or indirect access to external
memory areas that are unknown at the time of compilation.

36 </LibraryConformanceStatus>
37 <MemoryLayout>Optimized</MemoryLayout>
38 <ModifiedDate ReadOnly="true">2018-04-13T12:51:43.0092879Z</

ModifiedDate>
39 <Name>320</Name>
40 <Number>1</Number>
41 <ParameterModified ReadOnly="true">2018-04-10T07:28:52.155191Z</

ParameterModified>
42 <PLCSimAdvancedSupport ReadOnly="true">true</PLCSimAdvancedSupport>
43 <ProgrammingLanguage>LAD</ProgrammingLanguage>
44 <SetENOAutomatically>False</SetENOAutomatically>
45 <StructureModified ReadOnly="true">2018-04-10T07:28:52.155191Z</

StructureModified>
46 <UDABlockProperties />
47 <UDAEnableTagReadback>false</UDAEnableTagReadback>
48 </AttributeList>
49 <ObjectList>
50 <MultilingualText ID="1" CompositionName="Comment">
51 <ObjectList>
52 <MultilingualTextItem ID="2" CompositionName="Items">
53 <AttributeList>
54 <Culture>en-US</Culture>
55 <Text />
56 </AttributeList>
57 </MultilingualTextItem>
58 </ObjectList>
59 </MultilingualText>
60 <SW.Blocks.CompileUnit ID="3" CompositionName="CompileUnits">
61 <AttributeList>
62 <NetworkSource><FlgNet xmlns="http://www.siemens.com/automation/

Openness/SW/NetworkSource/FlgNet/v2">
63 <Parts>
64 <Access Scope="GlobalVariable" UId="21">
65 <Symbol>
66 <Component Name="320_ACC1_Occupied" />
67 <Address Area="Input" Type="Bool" BitOffset="29" Informative="true

" />

XXIII



E. XML code for safety zone 320

68 </Symbol>
69 </Access>
70 <Access Scope="GlobalVariable" UId="22">
71 <Symbol>
72 <Component Name="320/330_PIB" />
73 <Component Name="O_Blocking" />
74 <Address Area="None" Type="Bool" BlockNumber="2" BitOffset="88"

Informative="true" />
75 </Symbol>
76 </Access>
77 <Access Scope="GlobalVariable" UId="23">
78 <Symbol>
79 <Component Name="320_ACC1_Power" />
80 <Address Area="Output" Type="Bool" BitOffset="29" Informative="

true" />
81 </Symbol>
82 </Access>
83 <Access Scope="GlobalVariable" UId="24">
84 <Symbol>
85 <Component Name="320_ACC1_SpeedCmd" />
86 <Address Area="Output" Type="Int" BitOffset="1264" Informative="

true" />
87 </Symbol>
88 </Access>
89 <Access Scope="LocalVariable" UId="25">
90 <Symbol>
91 <Component Name="O_Occupied" />
92 </Symbol>
93 </Access>
94 <Part Name="Contact" UId="26" />
95 <Call UId="27">
96 <CallInfo Name="ACC" BlockType="FB">
97 <IntegerAttribute Name="BlockNumber" Informative="true">4</

IntegerAttribute>
98 <DateAttribute Name="ParameterModifiedTS" Informative="true">

2018-04-13T12:34:05</DateAttribute>
99 <Instance Scope="GlobalVariable" UId="28">

100 <Component Name="320_ACC1" />
101 <Address Area="DB" Type="ACC" BlockNumber="3" BitOffset="0"