SLC 5/01 losing program with power loss

unsaint33

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Join Date
Sep 2019
Location
MInnesota
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Whenever we lose power to the the machine, the PLC loses its program. But as you can see in the picture, the battery fault LED is not ON. Also, as you can see in the picture, there is no ROM. What do I have to do so the PLC retains the program through power cycle?

SLC500 1747-L511 B

INFO ON THE MEMORY MODULE:
40845-966-06
SLC500 111792
MDI CPU
FRN6B 1992

IMG_20210813_102903044.jpg IMG_20210727_074934399.jpg
 
More than likely the power circuitry in the plc which keeps the memory alive has failed. we have had this happen to four plc's. we send the plc out for repair. we use teamsesco. good price and they stand behind their work.
g.mccormick posted on the 15th that he had a slc 5/01 an other hardware he would ship to anyone needing it. here is the link.
http://www.plctalk.net/qanda/member.php?u=106376
regards,
james
 
James Mcquade said:
More than likely the power circuitry in the plc which keeps the memory alive has failed. we have had this happen to four plc's. we send the plc out for repair. we use teamsesco. good price and they stand behind their work.
g.mccormick posted on the 15th that he had a slc 5/01 an other hardware he would ship to anyone needing it. here is the link.
http://www.plctalk.net/qanda/member.php?u=106376
regards,
james
Click to expand...
James, so was it the CPU card, power supply, or the backplane that was bad in your experience?
 
I replace the power supply first at any sign of trouble like this, but if the rack contains a SLC analog card that has turned out to be the problem quite a few times.


And I remember only once it being the rack itself I had to replace, but once I discovered this I have never replaced a CPU for this since
 
Last edited:
All the stock parts for the power supply we have are 1746-P2. The width is bigger. Can I replace 1746-P1 with 1746-P2? Based on the SLC manual, P2 just has more current capacity than P1. But I just wanted to make sure.
 
If you open RSLogix and configure the PLC the software will suggest the size of the power supply, it depends on the rack size and the IO cards you have installed, that said I have had to use a smaller one on several occasions because of not having the correct one
 
geniusintraining said:
If you open RSLogix and configure the PLC the software will suggest the size of the power supply, it depends on the rack size and the IO cards you have installed, that said I have had to use a smaller one on several occasions because of not having the correct one
Click to expand...
Kind of a no brainer, but up-sizing from P1 to P2 shouldn't be a problem, right?

My picture is a screenshot from a SLC500 manual.

SLC500P.jpg
 
it was the cpu power components that was the issue.
some component(s) between the battery and the power to the memory went bad. even the reserve capacitor was effected.
we changed out the power supply, rack, i/o cards first. when it was repaired, issue was gone.
we had a spare and put it in service, but we tested the repaired unit for 6 months. no issues.
james
 
It's always good to hear feedback on these issues, so thanks. It fall in line with my general experience that the root cause being the power supply is more common than other valid causes.
 

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