SLC 5/02 Issue

-I have a SLC 5/02 that loses its program each time we cycle power off. We have replaced the battery, but this does not resolve the issue. Any ideas? I am tired of reloading programs.
-I am also having an issue with this SLC PLC not having the correct values for some machine settings (3 voltage settings for tension control). The SLC 5/02 is interfaced to a PLC-5. The PLC-5 is supposed to send the settings to the SLC 5/02. I can see the correct recipe settings on the HMI, but the SLC 5/02 has the wrong settings (and the drives controlled by the SLC output the wrong voltage). This is an intermittent issue and goes away without any explanation.
-With the program loss at power downs and this intermittent issue, I am suspecting a faulty SLC 5/02. I have SLC 5/03 5/04 on the shelf, but I am not sure steps involved in changing. Will I need different cables to interface to the PLC-5?

Does it have a memory module with no program in it?

How is the SLC 5/02 connected to your PLC-5? A PLC-5 does not support DH485 protocol.

It sounds more like a grounding or noise problem, to me.

I'm picky about the phrase "lost program". A user program in an A-B controller will be erased if it's found to be corrupt by one of the program checksum routines performed during boot and during runtime. A fault code will always be generated in such a circumstance.

I'm not saying that a defective or failing controller, power supply, or other component cannot cause memory corruption, I'm just saying that program "loss" is never the only symptom.

Do inspect the SLC for the presence of an EEPROM with a default program in it.

I am also interested in how the PLC-5 sends these setpoints to the SLC-5/02 controller. If there is a noise or grounding problem, the failure of MSG instructions might also be another symptom.

If you do choose to replace the controller as a diagnostic, it is very easy to convert from an SLC-5/02 to an SLC-5/03: just change the controller type in RSLogix 500 and download to the SLC-5/03. There are no features that I know about in the 5/02 that don't operate identically in the 5/03.

After you're sure grounding isn't an issue, grab an oscilloscope and test your power supply. We had an issue a few years ago with similar symptoms (program being erased), although it was a 5/03. The power was very "dirty". Changed the P2 power supply for a P4, I think, along with adding a powerline conditioner. Strangely, even though we had the program stored on EEPROM and bits set to always load from EEPROM, it didn't work...

I've also seen the problem occur with Micrologix-series. I don't know what the root casue is, but Im guessing it was caused by power surge from collapsing solenoid coils. Installing "snubbers" seems to have helped, since the problem has re-ocurred.

Is the program lost? Or you just seeing the 5/02 in a hard fault condition after you cylce power? We had the same thing happing and everyone claimed the program was lost, when in reality all we had to do was unplug the battery and cylce power and the plc would come out of fault mode and start back up. We found that we had a grounding issue.

Fisherjames73 said:

Is the program lost? Or you just seeing the 5/02 in a hard fault condition after you cylce power? We had the same thing happing and everyone claimed the program was lost, when in reality all we had to do was unplug the battery and cylce power and the plc would come out of fault mode and start back up. We found that we had a grounding issue.

Click to expand...

In my situation, the complete program was wiped clean. When I went on-line, the processor had "DEFAULT" as the program name (or something like "DEFAULT") and only one rung.

We do not have a memory module installed on this SLC 5/02. My understanding is if the battery works, you shouldn't need a memory module for storing the program. Is this correct?

Regarding the communication, we have a DCM module installed on the SLC 5/02. The wires from the DCM travel to the PLC-5 cabinet and are connected into CH1 on the PLC-5.

With all of the replies I received, I am starting to suspect a ground issue. This probably explains the intermittent issues we have with the SLC losing communication with the rest of the machine. When this happens, the SLC does not update when new settings are selected via HMI. It always "fixes" itself eventually.

If we power the machine down, the SLC 5/02 starts back up with a processor fault. When I log on via RSLogix, it indicates there is no program. I have to reload it from the programming laptop.

As I mentioned in my previous reply, the SLC communicates via a DCM module that is wired into CH1 on the PLC5.

A little over a year ago, I had the same thing happen to me. The only difference was it was a 5/01 and a stand alone. But as far as the symptom of coming up with a fault and "no program" (the program IS actually there you just can't get to it) it's a perfect match. Change your power supply and all will be well.

BTW, you should actually thank Ken Roach for suggesting the power supply to myself when I posted my problem last year. In the unlikley event the power supply is not the problem, I wouldn't thank either of us.

Thanks for all of your suggestions. We changed out to a slightly larger power supply that we had on the shelf from a decommisioned piece of equipment. We no longer have issues losing the program, and we have not had any intermittent "loss" of communication.

-Thanks again,
Chris

Great that you posted back with your solution.

That will surely help others who may experience the same problem.