SLC Losing Memory

Brijm

Lifetime Supporting Member
Brijm
Join Date
May 2006
Location
St. Marys, PA
Posts
645
I have a customer with a SLC 5/04 that is losing memory on Power down. We have changed the battery, power supply, cpu, rack, and the I/O modules.

It does seem like when we power down, about every other time, we will have a solid fault LED, and must power down again, before I can communicate with the PLC to download.

I remembered seeing about the grounding causing memory loss here, so I have him checking that (I don't believe there was a ground to the chassis). I've never seen about the hard fault however (solid LED).

I suspect the ground may take care of it (we've changed everything else); but, wanted to see if this sounded familiar to anyone. All I could find in the AB knowledgebase pointed to the power supply, and CPU/

Thanks,
 
This may be a stupid question, but are you losing the program on power-down, or are you loading a blank program on power-up ? I have more experience with Omron and they had a dip-switch setting to load the program from a memory module on power-up. S:1/11 is "Load memory always bit" sounds like it might be the same thing.
 
Mickey said:
Is there surge protection on all inductive loads, if you have them?
Click to expand...

This is an existing installation, I do not believe that there are surge supressors on the inductive loads. However, the fault occurs when I power down, and when in program mode (No outputs on)
 
GlennA said:
This may be a stupid question, but are you losing the program on power-down, or are you loading a blank program on power-up ? I have more experience with Omron and they had a dip-switch setting to load the program from a memory module on power-up. S:1/11 is "Load memory always bit" sounds like it might be the same thing.
Click to expand...

This was an existing program, and has not been accessed by the end user.... I'll double check, but the program should be the same as it has been for years (including load from EEProm)
 
If you go to the Processor Status and the Errors tab it should show a hexadecimal code for what is causing the fault. Is the fault actually that there is not a program, or by downloading a backup are you clearing the fault?
 
Mickey said:
Inductive "kicks" occur when power is removed and or outputs are shut-off.
Click to expand...

I never took the CPU out of Program mode... The outputs where never turned on.
Also, no other equipment from this cabinet was running....
 
Last edited:
glenncovington said:
If you go to the Processor Status and the Errors tab it should show a hexadecimal code for what is causing the fault. Is the fault actually that there is not a program, or by downloading a backup are you clearing the fault?
Click to expand...

There is no program. Attached is the message, when I tried to go online. Also, Nothing or minimal equipment was running when this occured. Also I could consistanly cause the fault by cycling power. I'm leaning more and more towards grounding.
 

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