PLC 5/40E losing program

sparky_28

Member
Join Date
Aug 2019
Location
Ohio
Posts
2
Have a PLC5/40E that has a battery installed and a working battery warning light that is off with the battery plugged in. There is no memory module installed.

Following a several second power outage the PLC lost its program, I am told by the building maintenance manager this is not the first time that this has happened.

I attached a fault log if anyone knows how to decipher it.

Thanks
 
Power surges can cause this. I have installed UPS's to help cure this problem.

Check grounding and surge protection for all inductive loads.
 
Power surges, brown outs etc.... have wiped programs in the PLC5 and SLC platform at many of my sites. UPS is best solution, even a small one will help you ride out the "bumps".
 
Or install a memory card, and monitor the "memory was loaded" bit (dont remember which one). When the memory was reloaded, trigger an HMI alarm to notify the operator that he may have to check and reenter settings that may have been reset to default values.

But I guess a memory card for a PLC5-40E may be more expensive than a UPS.
 
Hi, and welcome to the forum. We had a lot of those PLC 5's out west where I worked, and like JesperMP said, we had EEPROMs in all of them. There were configuration options to "load from EEPROM" when recovering from a power cycle, plus the processors had a good battery. Maybe those EEPROMs are available on Ebay or somewhere. Hope this helps.
 
In case you go for the EEPROM:

To select "EEPROM memory transfers to processor memory if processor memory not valid." you have to set both switches 6 and 7 in the chassis backplane to ON.

Then in the PLC code you monitor S:10/3 "EPROM memory transfer at power-up". Use this to trigger the HMI alarm.
 
There are roughly 40-45 PLC 5's in the facility. The unit that is losing its program is housed in a control panel with another PLC 5. I will double check though that the grounding is good.

I doubt they will go for memory module, but they may be willing to try a UPS.
 

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