losing memory

Hey guys I'm having a problem losing memory with a compactlogix 5330 model #1769-L30 and I'm using RSLOGIX 5000. We will running fine and then it will just lose it. The battery back up is ok and of course we aren't losing power. I download a back up copy back into the processor and we run fine for a day or two then does it again. Has anyone seen this before?

No experience with compactlogix, but ..

Guesses:

Too much noise.
too little grounding.
Or both.

JesperMP said:

Guesses:

Too much noise.
too little grounding.
Or both.

Click to expand...

I'll add, surge protect your outputs.

I'll check them out.

Mickey said:

I'll add, surge protect your outputs.

Click to expand...

I am a little new to plc programming and I can understand putting a surge protector on the main power but why would you surge protect the outputs?

He must be thinking on the coils on contactors and solenoids.
It is a valid point.

dajohn6 said:

I am a little new to plc programming and I can understand putting a surge protector on the main power but why would you surge protect the outputs?

Click to expand...

Inductive Surge:
A surge in voltage caused by sudden interruption of current in an inductive circuit. See PDF

Now I understand.

dajohn6 said:

Hey guys I'm having a problem losing memory with a compactlogix 5330 model #1769-L30 and I'm using RSLOGIX 5000. We will running fine and then it will just lose it. The battery back up is ok and of course we aren't losing power. I download a back up copy back into the processor and we run fine for a day or two then does it again. Has anyone seen this before?

Click to expand...

I am on a job site with using Compactlogix L35E communicating to three other vendor supplied L32Es. Last night one of the L32Es lost its memory at 7:00pm when the plant was not even running and no other equipment was activated. I knew the PLC went down at that time, as my L35E monitors the Produced/Consumed connection with this PLC and if that connection is lost, our PV1000+ logs an alarm event.

The only issue I could see with this PLC , was the stepdown transformer feeding the panel. 600VAC comes into each vendors panels and each vendor must generate their own 120VAC. Our panel and the other two vendor's panels are all fed from the same source. The panel in question has a 350VA 600/120 VAC stepdown. Our panel has a 1000VA 600/120 VAC.
Maybe it is possible the stepdown is too close to the edge as far as supplying 120 VAC to the plc's power supply and several other panel mounted devices in their enclosure.

Ian

Of course, you purchased the Web Based "Compactlogix Memory Retention" license, 9350-1234-1876 from Allen-Bradley for $27,650.00.

(Couldn't resist)

Does the Controllogix have a 24V output on it's power supply? If so, are you using it? I have seen this very same scenario with Micrologix if the 24v supply was shorted. My understanding is that is a safety function of the PLC. It is based on the assumption that if the 24v suppply dies, memory is corrupt and the PLC should not restart without intervention. If this is not the case, have you considered a CV transformer? That would provide a very high level of isolation from the line as well as voltage regulation.

I exchanged the compactlogix processor with a new one we had on the shelf about a month ago. For now, this has cooled the fire there, but if it starts losing it's memory again I'll look for some of these tips that I got. I did however check for a 24v output on the power supply, which it has, and it is not being used. It seems to be working as designed.


"Retention what?"

I had the same problem with a Contrologix L61 processor. Kept loosing the memory, so i tried to update the flash, but it kept freezing on me. Firmware went back to default 1.9. Tried everything, but no avail. Endedup exchanging it for a new processor, as i just got it a day ago.New one seems to be working fine with no issues.