hello, can anyone here explain to me how to troubleshoot problems with this program? I used the case instructions but case 1 cannot move to case 2 

Best regards, 

Bagus

The program segment is too small to see the whole picture.

The guessing then: 
How is the first step initialized? Perhaps the "ScreenData".stepIOOI is over written back to 1 from somewhere.

Lines 143 to 157 is executed. After scanning the code, the program exits the CASE. Line 152 is not executed in that scan. The CASE works like the Pascal language instruction and not like the C++ SWITCH instruction.

The value set in line 156 is scheduled to be evaluated by line 142 in the next cycle. But even before the line s 137 to 139 executes. This will override the step value back to 1. That means the CASE never sees the step value of 2. 

The evaluation in line 137 is causing the problem you ask about.

The future problem are the timers "ScreenData".Timer<n> used in the program. Make a study of how IEC-Timers work. The timer IN parameter needs to see a transition from FALSE to TRUE to work properly. Consider pulling the timers outside the CASE.

qwazee

The evaluation in line 137 is causing the problem you ask about.