1769-L33ER Processor not Talking to I/O Modules

Hi there,

I have 1769-L33ER Allen Bradley processor suddenly stopped running the plant. No indication of faults. Processor running okay with OK and Run LEDs on. Did all basic troubleshooting steps but the issue still exist and I cannot run the plant. Connected on line and checked no faults exists in Fault Table.

I did some simulation and found that Processor is not talking to the I/O modules.

What could be the problem?

Thanks for your help.