urgent -SLC 5/04 CPU-LEDs all lit

Skidood

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Oct 2016
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Hi all

My client in a very remote location is reporting that all LEDS on their CPU are looping...here is his exact words:
"the attached photo of modules in panel seem to be doing a constant loop, this photo shows all lights lit but then they all go out and the red one lights up, then the yellow one, then all the lights and this repeats this cycle every 7 seconds."

Here is a photo of the LEDS while they are lit up, if that helps at all.

And shouldn't the analog module have a green LED instead of a red one?
They did have some power disturbances on the previous working day but the PLXC was not powered up all day.
 
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not sure why the photo I attached isnt showing up but the red one he is referring to I believe is the Fault LED and the yellow one is the Force LED

And MY MISTAKE, it is UNCLEAR whether the PLC was powered up during he power disturbances. It has a 24 VDC power supply on the left end.
 
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Typically, these unusual LED indicator sequences indicate that either a hardware or software error has occurred.

If the FAULT and BATT LEDs are prominent at the end of the apparent sequence then this will indicate one of several possible software errors.

If the FAULT and FORCE LEDs are prominent at the end of the apparent sequence then this will indicate one of several possible hardware errors.

As the sequence you/they have described here appears to be a hardware error, then the root cause could be anything from the processor module itself, the power supply module, the supply to the power supply module, an I/O module, or the chassis itself.

Have you/they got a recent copy of the project file for this controller?

Have they got any spare parts?

Are they experienced enough to work on removing/replacing parts, resetting the processor, loading a fresh copy of the project, etc.?

Or are you or someone else experienced going to have to travel there to root cause and try resolve this?

If they are capable then you could instruct or direct them towards the following information...

14988 - SLC 500: LEDs flashing in unusual sequence that is not shown in the manual
Access Level: TechConnect

That one just explains a couple of possible sequences and just a processor reset (memory clear) as a possible solution, else replace the processor. However, there are other eliminatory steps I would recommend before definitely replacing the processor, and these steps do include replacing the power supply module, among other hardware, such as I've suggested above...

16289 - Troubleshooting hardware or application for a SLC 500 with fault led in solid red or flashing
Access Level: TechConnect

Regards,
George
 
Glad you got it figured out.
I am not trying to start a fight here, so please take this or leave it kindly.
When I see a post marked Urgent, my first inclination is to keep on scrolling.
 
Typically, these unusual LED indicator sequences indicate that either a hardware or software error has occurred.

If the FAULT and BATT LEDs are prominent at the end of the apparent sequence then this will indicate one of several possible software errors.

If the FAULT and FORCE LEDs are prominent at the end of the apparent sequence then this will indicate one of several possible hardware errors.

As the sequence you/they have described here appears to be a hardware error, then the root cause could be anything from the processor module itself, the power supply module, the supply to the power supply module, an I/O module, or the chassis itself.

Have you/they got a recent copy of the project file for this controller?

Have they got any spare parts?

Are they experienced enough to work on removing/replacing parts, resetting the processor, loading a fresh copy of the project, etc.?

Or are you or someone else experienced going to have to travel there to root cause and try resolve this?

If they are capable then you could instruct or direct them towards the following information...

14988 - SLC 500: LEDs flashing in unusual sequence that is not shown in the manual
Access Level: TechConnect

That one just explains a couple of possible sequences and just a processor reset (memory clear) as a possible solution, else replace the processor. However, there are other eliminatory steps I would recommend before definitely replacing the processor, and these steps do include replacing the power supply module, among other hardware, such as I've suggested above...

16289 - Troubleshooting hardware or application for a SLC 500 with fault led in solid red or flashing
Access Level: TechConnect

Regards,
George

Thank you very much....I dont have a TechConnect contract...it doesn't make sense for me to purchase that since I very rarely have to worry about PLCs....I am not a PLC engineer, I just take care of equipment that sometimes has PLCs as the control system. I do have the program and RSLogix....praying I wont have to go up there. They won't have any spare parts but they should be able to replace the power supply themselves if it comes down to that.
 
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Note: the current hardware error will have cleared the processor's memory and locked down the communication ports. Also, the processor won't be communicating across the local backplane to the likes of the analog I/O module, so that is most likely why the module does not appear healthy.

They can certainly purchase replacement parts and start replacing them. It could prove to be something other than the power supply, although they have been known to degrade after many years. But that can all take some time and end up being quite costly, relatively speaking. So first, and as a minimum, I would advise that they should clear out the I/O modules from the processor chassis and try to perform the processor reset to clear the hardware error and get just the FAULT LED flashing again, ready for the project to be downloaded. This would at least let you know you have a fighting chance with this processor. Still, a dodgy power supply, or chassis, could still prevent the processor from recovering. Sometimes a simple removal and reinsertion of the processor module can make the difference, but a processor reset will still be required to clear the hardware error.

If it does reset then it still does not mean that the error won't happen again later, depending on what caused it. But if reset, they can then power down and refit the local I/O modules one by one, powering down in between each one, until, hopefully, they are all fitted and the processor remains with just the FAULT LED flashing.

Then, if successful, you or someone will have to connect to the controller and download the project again.

For instructions to perform the processor reset, please see the below previous thread...

Allen Bradley SLC 5/03 strange fault state - I need help with the LED diagnostics

Regards,
George
 
Update...cause appears to be memory corruption with a good battery....the CPU had an EEPROM memory module, so all that was needed was to short out the VBB and GND and the program transferred upon power-up.. The machine has been running fine for 2 weeks now. Customer now has a spare CPU and DC power supply for future use as needed.
 
That is all good news!...

...that it successfully reset to healthy...
...that there was an EEPROM to reload the program...
...that you didn't need to travel to site...

...that that's that...

...OK, that is enough of that...

...and I hope that it lasts...

...oh, sorry, that was the last that... šŸ™ƒ :oops:
 
...that was unfortunate, but still, a good outcome and well done.

Fingers X'd it doesn't reoccur.

G.
 

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