Understanding debugging tools and techniques

There are many different tools and techniques that can be used to debug a program. As was discussed at the beginning of the chapter, some techniques are more sophisticated than others. It doesn’t matter which technique you use as long as you debug the software and it works as intended. As such, the following section will explore some ways to track down problems in your code.

Print debugging

The easiest way to debug a program is with print statements. Print debugging is used to isolate problems; in other words, this technique will help you find the offending code. The IEC 61131-3 doesn’t support a command that will output to a console or screen the same way languages such as Java or C++ do. However, this technique can still be used in PLC programming, and in some regards, it is a little easier to use. To demonstrate the use of print debugging, we are going to create a simple program that toggles a variable to TRUE when...