SLC500 fault diagnostics

roussey

Member
Join Date
Jul 2011
Location
Brazil
Posts
13
I am having a problem with a SLC 5/03 processor that is faulting but I don't know why. It simply fail. I want to know if there is any way to,look at the history of failure.

Thanks
 
Roussey,

If you take a look at your data files there is one which will be S2-Status.

If you open that Data File you can look at all errors which are on the processor.

Also if it is a major error, I believe you can got to the Online/Offline box in the top left corner, and this will give you an option to go to the place which is causing the error.

Hope this helps

Mark
 
Thanks Mark.

The error code is 21h. 'remote power failure of an expansion I/O rack'. Do you have any idea of what is causing that. It is a SLC 5/03 processor.
 
Thanks Mark.

The error code is 21h. 'remote power failure of an expansion I/O rack'. Do you have any idea of what is causing that. It is a SLC 5/03 processor.

Do you have more than 1 rack or remote I/O?

Also check out page 16-6 of the SLC Instruction Set manual. This is publication 1747-RM001D.
 
Last edited:
That's the weird thing: there is no remote chassis. It's a A-13 chassis. I had this problem before, it was a A-7 chassis and I changed to A13 thinking that this would solve the problem. But it seems not.
 
Well, one of the things I have learned is that a lot of the time the fault codes don't really help that much. It's possible you had a momentary power drop out which can generate almost any fault code. Sort of like playing Wheel of Fortune. I recently have had to go troubleshoot plc faults at 2 customer locations. The first location had a ML1000 and the fault was "unexpected result at end of scan". Now how helpful is that? It ended up being a hardware failure. The second location had a 5/05 and the fault code there was something about a watchdog error. The customer said they had a storm the day before with a nearby lighting strike. I cleared the fault and it's been running about 2 weeks now with no issues. Again, my theory was a power surge or, more likely, a power cycle or multiple power cycles in a short time. None of this may be of help to you but I thought I would pass it on.
 
Well, one of the things I have learned is that a lot of the time the fault codes don't really help that much. It's possible you had a momentary power drop out which can generate almost any fault code. Sort of like playing Wheel of Fortune. I recently have had to go troubleshoot plc faults at 2 customer locations. The first location had a ML1000 and the fault was "unexpected result at end of scan". Now how helpful is that? It ended up being a hardware failure. The second location had a 5/05 and the fault code there was something about a watchdog error. The customer said they had a storm the day before with a nearby lighting strike. I cleared the fault and it's been running about 2 weeks now with no issues. Again, my theory was a power surge or, more likely, a power cycle or multiple power cycles in a short time. None of this may be of help to you but I thought I would pass it on.

Along the same line of thinking, power surges can cause all sorts of strange problems.
Make sure your equipment is grounded properly and surge protection on all inductive loads.
 
The output card is a TRIAC model switching 220Vac relays. When you say surge protection in this case you are saying that it would be good using Snubbers?
 
The output card is a TRIAC model switching 220Vac relays. When you say surge protection in this case you are saying that it would be good using Snubbers?
More like the power being used by the CPU itself. Brownouts, rapid on offs of power going to the processor has a tendancy to create random errors. Look for line conditioners or UPS Power Supplies. Also a dedicated circuit just for the PLC CPU is generally not a bad idea.
 

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