POUs for Implicit Checks

Overview

You have to add special POUs below an application to provide implicitly available check functions. They verify array and range boundaries, the validity of pointers and verify the presence of division by zero during runtime.

NOTE: The availability of the check functions have a runtime performance impact.
NOTE: For the check functions to verify the code of uncompiled referenced libraries, you have to enter the Compiler defines string checks_in_libs in the Build tab of the Properties dialog box of the application.

To add monitoring functions under an application, select the application node in the Applications tree and click the green plus button or execute the command Add Object > POU for implicit checks....

The dialog box allows you to activate the following check functions for the selected application:

Category

Added functions

Bound Checks

CheckBounds (for arrays)

Division Checks

Range Checks

LRange Checks

Pointer Checks

CheckPointer

When you insert a check POU, the option is no longer available in the dialog box to help avoid a double insertion. If the different types of check POUs have been added below the application, the Add Object dialog box does not provide the POUs for implicit checks option any longer.

 CAUTION
INCORRECT FUNCTIONALITY
Do not modify the declaration part of an implicit check function in order to maintain its functional integrity.
Failure to follow these instructions can result in injury or equipment damage.
NOTE: You may, however, add local variables to the declaration part of an implicit check function.
NOTE: After having removed implicit check function (such as CheckBounds) from your application, no Online Change is possible, just a download. A corresponding message is displayed.