Hi guys,

I have an SLC 5/03 CPU in a 10 slot IO chasis; slot 4 and 9 are free. The PLC is giving fault 21h 'remote power failure of an expansion I/O rack'. I changed the power supply unit, the CPU and also pulled out all the I/O wiring. Still the same. It faults the moment I put in RUN mode. When I download program and stays in PROG mode, it doesnt fault. This is why I havent tried changing the chasis.

Any suggestions guys?

Best Regards,
Irah

See link below

http://rockwellautomation.custhelp.com/cgi...amp;p_topview=1

Thanks for the reply Mickey...I removed all the I/O modules in the chasis and placed the CPU in RUN mode...it faulted with the same code...now what do i do...could it be the chasis?? i didnt download a blank program though...will try that also...

Regards,
Irah

If don't use the blank program process it will fault because the modules are not there. If you have a module in the I/O configuration it needs to be installed or the processor will fault when you go to run mode. Do what the link tells you to do and you should find your problem.

Sorry for the delay. It was my day off yesterday. Ok its wierd. I tried inserting the modules 1 by one and downloaded the blank program for each one after IO configuration. No fault in any of them. CPU going to RUN. Then I put back all the modules, downloaded the original program. After I put in RUN mode, the CPU faulted and cleared itself twice (I'v read this is a self clearing fault). Then after this its working ok. Even tried running the machine. Its been 5 hrs and no fault yet. Is there any other procedure to know which slot is causing the problem incase it faults again?

Are one or more of the cards a 1746-OW8 if so see AB Knowledge base below:

No OW8..heres the configuration.. 1746 A10 Chasis; L532B 16k os301 CPU; OBP16 x 2nos; OW16; IB16 x 4 nos

1746-OW16 same thing twice as many outputs. Do you have surge protection?
Not saying this is your problem but it can't hurt to have them.

hmm...I dont think theres surge protection...so you suggest I replace this module incase this reappears huh...

I personally have not experienced the problem you are having. I am just a messenger here passing along a AB knowledgebase article. But if you have a spare it can’t hurt to replace it.

And its always wise to use surge protection.

thanx a lot Mickey..really helpful..bye...tc...see you around

I don't think I'm going to be able to make over to the United Arab Emirates anytime soon. But when I do I
will be sure to look you up.