IEC 61131-3 Debugger

Introduction

The IEC 61131-3 Debugger allows you to step through and test IEC 61131-3 code:

The debugger window contains four sections. From top to bottom, the four sections are:

Section	Purpose
Debug Toolbar	Controls how the debugger steps through the code.
Module List	Displays the names of the source code files relevant to a debug session. Allows you to switch between source code files.
Source Window	Displays the current source code file and current execution location. Allows you to set and clear breakpoints in the code.
Variable Window	Displays the variables in scope at the current location. Allows you to change variable values.

Starting a Debug Session

You can start an IEC 61131-3 debug sessions from:

The Graphic Editor Debug Tool.
The Toolbar Editor Debug Tool.

Debug Toolbar

The debug toolbar provides you with commands to step through IEC 61131-3 code:

Command	Description
	Stops execution immediately.
	Restarts execution from the start of the program or script.
	Continue execution until one of the following occurs: The Break button is pressed. A breakpoint is reached. The program or script completes.
	Displays the current source location.
	Steps into a function call.
	Steps over the current line.
	Returns from the current function.

Module List

The Module List provides the list of source code modules referenced by the current script. To display the source code for a module: select the module from the list. To return to the current source location: click the Display Source Location button in the toolbar.

Source Window

The Source Window displays the code you are currently running through the debugger:

From left to right, the Source Window has three areas:

The debug marker area.
The line number area.
The source code area.

The Debug Marker Area displays debug markers in your code:

Marker	Description
	Shows the current execution location.
	Shows the location of a breakpoint.

To set or clear a breakpoint click the Debug Marker Area. Note: The debugger will only allow you to set breakpoints on source code lines that correspond to actual code. For example you cannot set a breakpoint on lines that contain only whitespace or comments.

Variable Window

The Variable Window shows the program variables that are in scope for the current source code location:

To change a value do one of the following:

Click BOOL values to toggle between TRUE and FALSE.
Click other values to start an in place text editor. Enter a new value then press Return to confirm the new value.

Further Information

Common Elements

To learn about IEC 61131-3 Common Elements you can use in Structured Text (ST) programs and functions.

Glossary

For the meaning of terms used in Fernhill SCADA.