SLC5/04 Fault 0002

Greetings.

I was installing a 1746-NIO4V in an unused slot (7-slot rack) to support a new project. The processor is a 1747-L541 with DH+. Dip switches set for voltage. Set the I/O configuration for the new module and successfully downloaded. Returned unit to RUN mode with no problems. I went offline, programmed some rungs to check functionality, they successfully verified and I then downloaded. The unit went to RUN again, but after toggling the two control bits that made the analog output rung go true, I immediately lost communication over DH+. My initial attempt to go in through RS-232 didn't work either, but can now see the unit with DF1.

When I attempt to go online, I get a persistent 0002h fault and prompt to download. When I try to download, I just get the old DiagnosticStatus Failed: 0x4 message.

I put a brand new 5/04 in the chassis and got the same result (after one initial 0001h fault). I tested both the original 5/04 AND the NIO4V module in a spare rack and they work fine. The 24V fuse checks good on the rack power supply.

I checked this link but it didn't shed any new light on my problem. http://www.plctalk.net/qanda/search.php?searchid=427806
Could I have lost a backplane voltage?

Any thoughts or suggestions would be greatly appreciated.

Grover

Just an update. After swapping power supplies with another rack and de-populating the failing rack (to no avail), I ended up putting the original pieces back in place. After some time I was able to communicate with the original 5/04 over DF1 and downloaded the program. All the programming changes I had previously made were accepted and ran without fault. I don't know what actaully caused the original fault, but am glad it is working at this point.

Grover