PLC Programming

A Brief Introduction to CoDeSys
1 A Brief Introduction to CoDeSys
1.1 What is CoDeSys
CoDeSys is a complete development environment for your PLC. (CoDeSys stands for Controlled
Developement System).
CoDeSys puts a simple approach to the powerful IEC language at the disposal of the PLC
programmer. Use of the editors and debugging functions is based upon the proven development
program environments of advanced programming languages (such as Visual C++).
1.2 Overview of CoDeSys Functions...
How is a project structured
A project is put into a file named after the project. The first POU (Program Organization Unit) created
in a new project will automatically be named PLC_PRG. The process begins here (in compliance with
the main function in a C program), and other POUs can be accessed from the same point (programs,
function blocks and functions).
Once you have defined a Task Configuration, it is no longer necessary to create a program named
PLC_PRG. You will find more about this in chapter 6.7, Task Configuration.
There are different kinds of objects in a project: POUs, data types, display elements (visualizations)
and resources.
The Object Organizer contains a list of all the objects in your project.
How do I set up my project
First you should configure your PLC in order to check the accuracy of the addresses used in the
project.
Then you can create the POUs needed to solve your problem.
Now you can program the POUs you need in the desired languages.
Once the programming is complete, you can compile the project and remove errors should there be
any.
How can I test my project
Debugging
Once all errors have been removed, activate the simulation, log in to the simulated PLC and "load"
your project in the PLC. Now you are in Online mode.
Now open the window with your PLC Configuration and test your project for correct sequence. To do
this, enter input variables manually and observe whether outputs are as expected. You can also
observe the value sequence of the local variables in the POUs. In the Watch and Receipt Manager
you can configure data records whose values you wish to examine.
In case of a programming error you can set breakpoints. If the process stops at such a breakpoint,
you can examine the values of all project variables at this point in time. By working through
sequentially (single step) you can check the logical correctness of your program.
Additional Online Functions
Further debugging functions:
You can set program variables and inputs and outputs at certain values.
CoDeSys V2.3 1-1