PLC 5/60 processor fault

Morning all, I've got an issue with a plc5/60 processor that keeps losing the program everytime the panel is powered down.
When the panel is powered up again, the processor led is red and steady (indicating major error) and the program is gone (processor shows default on rs linx).This fault has only occurred recently, the processor etc has ran happily for the last 3 years. Reloading the program is no hassle and the processor runs quite happy again, until the next time the power is off!.

The battery has been replaced for a new one and i've checked the processor and cards are seated properly, supply to the rack is good etc etc.

I suspect the processor is on its way out, but i'm wondering if there are any more checks i can do before swapping the processor out?

Any advice on something i may have missed?

Cheers.

Bolty.

Did you check the new battery to see i it is good? If sure the battery is good must be something that is not letting it power the ckt i.e. problem with the processor.

Cheers for the quick reply.

The processor battery is good and healthy. Just after i posted my question,i had another look at the battery and connections, and everything tests out fine. If you remove the battery, the battery led comes on. The processor also flags up the low battery warning in the status table, so would seem to indicate that the battery is detected but doesnt seem to hold the memory when powered down.

Hmm..Time to swap out the processor methinks.

Thanks

Bolty.

Years ago I was at a plant that was automating their equipment with AB PLC5. The engineer over the project used a refubished unit in the beginning, we had started having a similar problem of it losing the program when shutdown.

Since we were running 24/7 the problem was minor but then it started getting worse i.e. losing program while running, eventually lost the program and would not let me reload or go online.

It was kind of funny when it went out. We had a PC that was full time connected with its own phone line and a program called Closeup (similar to pcAnywhere). The engineer was in Boston while the plant is in Birmingham, AL, it took me 4 hours to get through to him I could not go online with the processor, he just kept wanting to know why he could not get online using the dial-up aspect.

**Bolty** said:

Cheers for the quick reply.

The processor battery is good and healthy. Just after i posted my question,i had another look at the battery and connections, and everything tests out fine. If you remove the battery, the battery led comes on. The processor also flags up the low battery warning in the status table, so would seem to indicate that the battery is detected but doesnt seem to hold the memory when powered down.

Hmm..Time to swap out the processor methinks.

Thanks

Bolty.

Click to expand...

Before changing the processor I would change the AB power supply. Double check the quality of your incoming power.
The only time I have seen this was due to poor quality incoming power. A UPS took care of problem.

Again, thanks with the quick responses.

I'll give the swapping out the power supply a try first (i was pondering this anyways..heh) and see what happens. I'll get the spare 5/60 processor out of the stores anyway incase the it still faults.

The incoming mains isn't really an issue as the traces always show up pretty clean, and the factory has power correction gear fitted at the 11kv incoming to help even further. If i suspected the mains was a problem, i would expect to see the numerous other plc / slc / clx processors having random probs too.

I'll try the ps and see what happens later in the week. until then. the techs on shift will just have to reload the program if the have to power down the panel.

Cheers

Bolty.

Memory modules are also nice to have. Sit to reload on power up.

Take a look at the status file and see what the plc thinks the rack DIP switches are set to. Two of those switches tell the plc what EEPROM upload mode is used. One of those modes is load on power-up. I think if that mode is selected and an EEPROM is not present the program gets whacked.


This spring I had a PLC 5/20 start doing something similar. In my case the processor had an EEPROM. The only way I found it was I was making program changes and had to power down before I could write the EEPROM. When I powered back up my edits were gone. The processor indicated upload on power-up. When I looked at the backplane switches they looked like they were in the right positions, upload on bad RAM. I just toggeled them all and things have been working ever since.

Keith

The dip switches have also been checked over. The dip switch settings are fine and they haven't been altered in any way since i was involved in the panel commissioning 3 years ago (Checked my old commissioning notes, dip switches are exactly as i had recorded.) This processor problem has only manifested itself in the last 7-8 days. Until then powering down and up has never presented any problems.

I'll gave all your gratefully recieved suggestions some thought and see if i can suss out whats faulty on thursday. (Day off tomorrow to continue rewiring the house..heh. A sparkies work is never done!)

I'll feedback some findings when i get a chance to see whats playing up. My bets on the 5/60 processor.

Thanks all.

Bolty

I don't want to beat a dead horse, but note that I didn't say the switches were changed. The processor intepretted them as changed. The only way to know what the processor is seeing is to look under the 'Switches' tab in the processor status.

In my case corrosion or dirt had caused the plc to see switch settings other than those the switches actually had.

Keith

Apologies mate, i misunderstood. I thought you were talking about the dip switches being moved, not what the actual processor interpreted them as! D'oh! (it's been a long day..heh). I've never considered that as a type of fault before. I'll make sure to double check the switches tab when i'm back to work on thursday and make sure both the dip switch settings and what the processor sees tallys up.

Cheers, (back to my nice cold beer!)

Bolty.

If all the aforementioneed checks out, you may look very closely at the battery connector.


I had one with similar symptoms years ago with a bad connector to the battery that caused it to be intermittent.

EDIT: I also had some rack dipswitches act up just like Keith described...different symptoms though...flipping them back and forth a few times cured it...

I've got a 5/60 that is refurbed and has the same issue.
Thank God it is on our Test unit.
I have checked, rechecked the battery, replaced it, checked all dip switches, and PS. No issues.
But sometimes when the test bed gets shut down, I mean momentarily, the programs disappears!
No Eeprom either.
I can't seem to solve our problem either......

Morning all, Just a quick bit of follow up to let you know the conclusion of my plc 5/60 processor fault.It was the 1771-p7 power supply at fault. I checked status table, dip switches on both rack and processor, retested battery and connections. Reseated processor, modules etc but none of these made any difference.Program would still disappear.

I then swapped out the processor, loaded the program, powered down and again no program on power up. Swapped back the old processor, then swapped out the power supply and loaded in the program again. Powered down the panel, counted to ten (heh) then powered up and voila, processor on a steady green and the program still there!!.

So, thanks all for the suggestions, especially the dip switches. Would never have thought of that as a possible fault, but a pint goes to mickey for getting the correct fault although you'll need to come over here to get it though.

Cheers all

Bolty.

I just went through a similar hair pulling problem with a 5/25. The cure in my case was the PS as well. Don't ask me why.........