SLC 5/04 keeps changing nodes

[andresbdv]

We're using a 64K memory SLC 5/04 CPU. One day the program suddenly got erased from the CPU, causing the process to activate the emergency stop. We plan on migrating the project to ControLogix but we're still missing some hardware. Meanwhile, we decided to change the CPU, being the only difference the memory. We installed the same CPU, except the new one was a 32K memory CPU instead of 64K. After downloading the program and establishing connection with the Panel View that it's connected to, the PLC automatically changes nodes after some hours or days, losing once again connection with the Panel View.
I'm not a PLC expert and correct me if I'm wrong, but I would guess that the problem is the new CPU's memory because we never had this problem with the original CPU.
Any help is appreciated, thank you!

 

[widelto]

"The PLC automatically changes nodes after some hours or days."
That means you have some kind of network, please elaborate.

 

[Mickey]

Does the SLC have a memory module?

 

[I_Automation]

Since the 5/04 uses a DH+ network is it possible there is something else with that node number that causes the SLC to use another open node? [W.A.G. here as I've never seen this]


Like Mickey says, maybe the program was downloaded to the EEPROM before the node number was corrected and something is causing the PLC to reboot [Analog card taking the rack power supply down is my main culprit] and it's set to load from EEPROM every boot, not just if memory is corrupt.

 

[dummy_bit]

If you have surges and spikes in your incoming power, the SLCs tend to dump the program and reboot with fault. I've had to install many isolation transformers due to our incoming power.

 

[RedSoxFan3]

The SLC 500 is a really quirky platform. I don't like it too much. It's no PLC5 or CompactLogix.

Anyway, the SLC 5/04 should have EEPROM. If you don't take care of the battery and you have a power bump, you will load off the EEPROM.

There's a way to write the existing project to EEPROM in RSLogix 500. I haven't done it before, but there's definitely a way to do it.