Monitoring local variables for user-defined functions and user-defined function blocks

Troubleshooting user-defined functions (UDF) and user-defined function blocks (UDFB) differs from normal program monitoring because their logic might execute multiple times per scan.

When connected to a

Micro800

controller, you can:

Monitor UDF and UDFB variables in the variable grid by double-clicking

Local Variables

in

Project Organizer

.

To view the input parameter values for each instance, refer to the values of the variables that are being passed into the instance.

In the following example, program SIMPLE_MOV_POU calls a UDF four times and the local variables are updated with four different values. To monitor each execution of the UDF, additional input logic must be added for each UDF to be executed once at a time.

When monitoring the internal logic of the following UDF, only the last executed UDF is shown for the local variables (

SIMPLE_MOV = 4)

. To monitor or troubleshoot each execution of the UDF, additional input logic must be added for each UDF to be executed once at a time.

The following example, program Prog1, calls two separate instances of a UDFB. When monitored from the graphical ladder view, 1 is shown as the value being passed into FB1_1; when monitored from the variable grid, 2 is shown as the value for FB1_1.InputParameter. To monitor variables when passing values of sub-elements of arrays or structures  into a UDFB, use the graphical view.