PLC5/20 faulted

One of our customers has a PLC 5/20 hot backup system installed and running for around 2 years. Just yesterday received a call saying that one of the processors has faulted. Visited the site today but couldn't establish communication with the PLC either through RS232 or through DH+.

The status of the LEDs on the processor is as follows:
BATT - OFF
PROC - solid red
FORCE - OFF
COMM - OFF
CH 1A and CH 1B - solid red

From the manual, I understand that it's a hardware fault and I need to replace the processor.
Has anyone come across something like this?

Did you toggle the keyswithch to program then back to run?

Another thing to try is turn power off, pull processor out of rack, and re-seat, turn power back on.....

If you can get communications, Download a known working copy of the program.

93lt1,

tried that, but still no change, the LED status remains the same.

AB

I had this problem once and had to unplug all com cables in order to establish com through DH+. The battery had gone bad on my processor
(with no indication from the batt led) and the processor had lost the program giving the processor the hardware fault.
Make sure processor is in program........

Seems to me there was some difference with the plc5/20 compared to the others but I cant remember what it was now. I do know that the company I did work for had alot of problems with them along this line, they changed them all to 40's. I had one that regularly faulted and had to reload the program, eventually it did just what you are saying. There is a way to clear the memory and reload it (if you have a copy of it) but I cant remember or find the details involved with clearing memory. I think I saw it recently on here but cant find the post.

Anyway, if you can clear it and reload then your ok, if not the processor will probably have to be replaced. NOTE: AB offers an exchange/repair that is a little cheaper than buying new, talk to the local AB guy, they will usually ship it right to you and you send the old to them, no waiting till they recieve yours.

Do the lights come on and stay in this state even through power-up, or do you see some flashing or change of color?

mike, i will change the battery (hope i have a spare somewhere) and try.
rsdoran, i will have to look in the knowledgebase to find the reset procedure, if you come across it before me do let me know.
93lt1, the state of the leds remains the same through power up there is no flashing.

thanks for your help guys, will keep u posted.

ITs been a long time but I think with the PLC5 the memory is volatile so if you remove the battery (with power off) the memory will be cleared.

removed the battery and powered up, but still no change in LED status. looks like i will have to replace the processor.

The solid red Processor light indicates that the processor has lost memory. Normally all that would be necessary at that point would be to reload the program.

However.......with the Channel 1A and 1B indicators also being red, that's bad! That indicates a hardware failure. The fact that you removed the battery and still get the red 1A and 1B would pretty well confirm it.

Looks like you need to swap out a processor. As rsdoran pointed out, you can get an exchange unit by contacting your local distributor. An exchanged unit is a previously repaired unit that comes with (I believe) a 6 month warranty. They can usually get it to you next day. It costs a little more than repairing your processor, but it is a lot less expensive than buying a new unit.

OG

I not mistaken your problem as same as me.
What I have done.Troubleshooting can do online during the processoser
failure.look into a major faulty,where the code problem will indicated.Other alternative download again the new program.
Averything came back to normal.