Hi,

I would like to know how to create OB122 in my program?

Hello,

You can create just one OB with number 122. And download it empty in CPU . This will prevent the CPU to go in Stop mode in case of IO access error. Check at Programming with STEP 7 V5.4 and search for OB122.(Chapter 23). Look also at Which organization blocks do you need for error handling?

Best regards,
Hristo Mihalev