I have an old S5 CPU 103 that is stuck in STOP mode. Can someone help me diagnose the problem?. I suspect the CPU communication BUS with the I/O

Dear Autogen,

You must have 1 valid IO base connected to the PLC to go in RUN mode.

I suggest you disconnect the bus connector going to the second io base and power up after to see what append.

If PLC go in RUN, you can play the game "divide the problem in half" to find the bad hardware component.

Best Regards

Hello,

you should use the diagnostic a the STEP5-software or at your used software to program the S5 (e.g. S5 for Windows from IBHsoftec).

Then you can see what is the reason for your STOP of the CPU.

regards
CaOd

The interrupt STACK on IBHsoftec gives the message “Peripheral unknown"