I/O Access Error in my S7-400

Hello everyone,

I have problem with my S7-400. My CPU is going to STOP suddenly. When I check to diagnostic buffer it said "Event ID 16# 2942 I/O access error, reading". I also attached my complete diagnostic buffer.

My question is :

1. what actually happen with my CPU and make I/O Access Error happen?

2. why its going to STOP even i have requested OB (OB122) ? I think this requested OB is to prevent CPU STOP when error happen.

Hi,

Surely, Downloading OB122 should not cause PLC to go in STOP. I guesss, it's 'Event 36 of 3200: Event ID 16# 494D' that is responsible.

With insufficient info, I suggest you following:

1. Download only HW config for CPU and no program. Test it. Now without downloading program, only configure remaining DP slaves, compile and download. Test it. If it's OK, then no problem in hardware.

2. Now use compile all function in check block consistency.[Right click- Blocks]. It should be free of errors. Now program is error free. Download program now.

3. Also add OB121 and OB85.

To add some more info,

I believe the cpu has stopped due to OB82, OB82 will be called when we have failure or short circuit of the IO.

so load ob82 and check.

Hello,

Please if you solve the problem share it with others.