When runing a plant i have disturbance in my communcation so that whole plant trips . this is the old plant runing for past 5 years . I have checked the voltage going to the IO modules and repeaters every thing fine . And i have used OB85,OB 86, 0B87,OB 122 included in my program .I have attached the diagnose file.  I have also terminated the starting and ending node . pls give me the solution  .

The CPU is reporting a rack failure, i presume node 27 is remote I/O? Is it some type of ET200? The failure i think is in the remote I/O rack somewhere - faulty rear conector or faulty card. If you can tell us what node 27 is it will be easyer to help.

Cheers

Jon

Thanks for your reply . Yes node 27 is a remote DO card ET200L (6es7 132-1bh00-0xb0). 

whole plant is working normally suddenly this problem comes and back to normal in a ms . so very tough to see were the problem . how to conform that this rack is fault are card faulty .

thanks a lot ........