Siemens S5 CPU 922 Run and Stop LED Do Not Turn ON

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Thread Starter

Syed Waqar Azeem

I am using Siemens S5 cpu 922. When installed in rack and powered on, both the Run and Stop LED don't turn ON. The only light that is turned ON is BASP. I have tried removing all cards but this doesn't help. I tried changing the CPU with a spare 922, which I believe is healthy and is in new condition, but the same problem persists with this CPU. I also tried a CPU 928 but with this also, both Run and Stop LED remain OFF and BASP remain ON. From this I concluded that their must be a problem with Siemens rack. Since I don't have a spare rack I am not able to verify that.
 
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Kevin Frechette

Have you done a cold start by holding the reset switch up and cycling the run switch from stop to run.

A cold restart followed by a warm start is necessary to get the old S5 CPU cards running properly.

The BASP error is a major fault which requires a cold start to clear the error. A warm start by going from run to stop to run won't clear a BASP fault.

Just be careful because the overall reset (blank memory) is when you hold the reset switch on and cycle the run/stop switch twice.
 
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Syed Waqar Azeem

I have tried doing cold reset and warm rest on processor. The situation remain as such. Both STOP and RUN LEDs remain OFF.

What could be the possible reason for this behaviour? I am also not able to communicate to PLC through Siemens PG.

Thanks.
 
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Kevin Frechette

The only thing I can think of is that the Rack is faulted. The backup battery may be missing or dead. The rack needs a reset after power up.
Too bad you can't read the ISTACK errors with the programming software.

> I have tried doing cold reset and warm rest on processor. The situation remain as such. Both STOP and RUN LEDs remain OFF.

> What could be the possible reason for this behaviour? I am also not able to communicate to PLC through Siemens PG.
 
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Bob Peterson

We have started getting a fair number of service calls for S5 units. They are closing in on thirty years old or more. They are just near the end of their useful life. So far we have been able to find replacement parts for them, but it is not always easy. We are replacing them with S7 units or competitive spending on the customer choice.

Some times we find the processors have no program and no prom and no backup. You may get it back up and running this time but it would be in your long-term best interest to figure out what the more permanent fix is going to be.
 
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