PLC5-40E IO configuration

Here's a new one for me...

Over weekend, one of our plants went on the fritz. On Friday when we closed up everything worked fine, normal.

This morning when we opened we were greeted by lots of alarms. Looking closer, I found that none of the remote IO input cards were showing any input at all. When we look at the cards, there are all the inputs we would expect lit up, but none of it is making it to the processor.

We started checking the cabling, and didn't find any problems. I checked the channel configuration and it's gone. I don't understand what could make that happen, no one has access to these PLCs except for me, and I was not connected.

I have a backup so I know what the configuration should look like, and auto-configure worked just fine. The ethernet connection there sucks a little, so I hate doing much of anything remotely. It worked, though, so all's well that ends well. I don't have to deal with angry delayed truck drivers, so I have that going for me.

The thing is I would like to know how this happened so I can take steps to avoid it in the future. Anyone have any ideas?

Does the PLC have a memory module? If so does it have the latest program in it?

Mickey said:

Does the PLC have a memory module? If so does it have the latest program in it?

Click to expand...

It's only got the basic on board memory. Our facility isn't all that complex, although you might not know it to look at the logic itself.

I made a small change on the 13th, and saved it, and when I went online today it didn't hiccup at all. The IO was all working when I saved. I didn't check the IO on my copy before I connected, but it must have been there before that. I'm a little surprised that it didn't give me a mismatch dialog before it let me online.

Do you use any type of line filter going to the PLC5?

I worked in a department that had 100+ PLC5's and have seen my share of weirdness. The AB PLC5 series controllers are very sensitive to dirty power. Our installation was good but no installation is perfect. When we started up the shop we were getting odd faults like Ram Faults. We installed, at the suggestion of our AB representative, Emerson Islatrol IC+105, our cost about $150. Never got another Ram Fault and who knows what else.

Just a thought.

Sydney said:

Do you use any type of line filter going to the PLC5?

I worked in a department that had 100+ PLC5's and have seen my share of weirdness. The AB PLC5 series controllers are very sensitive to dirty power. Our installation was good but no installation is perfect. When we started up the shop we were getting odd faults like Ram Faults. We installed, at the suggestion of our AB representative, Emerson Islatrol IC+105, our cost about $150. Never got another Ram Fault and who knows what else.

Just a thought.

Click to expand...

I've had to install a UPS at the processor, we have some large equipment which causes some kerfuffle when we start it up. I don't have them on the remote racks, though.