SLC 500 major error 21h

[02js4130]

Hi,

We are having issues with an intermittent Major error code 21h. The plc can be running for varying amounts of time before faulting anything between 15 mins to 3 hours making it difficult to identify the issue. We have an SLC 500 with a 13 slot rack and p2 power supply. The cards are a mixture of input and output with analogue and thermocouple cards.

We have swapped the rack and power supply and the same fault appeared after 3 hours. Is there any way of identifying which module is causing the issue?

thanks in advance

 

[BOWILLY]

Rtfm

 

[Thysia]

Apparently you should check the battery in your SLC.

 

[Mickey]

Here is what the book says..

 

[02js4130]

Thanks for the answers I have checked the battery it's reading 3.6v , I've also read the manual and it doesn't indicate anywhere which module is the issue. All the modules have been taken out cleaned and relax seated same issue happens. It's a bit difficult to find an issue on a running process when the error can take up to 3 hours to occur.

 

[OkiePC]

I believe that error points to an expansion rack power supply problem.

Is there an expansion rack connected to the SLC?

If not, I usually find analog cards are more likely to cause errors than simpler discrete I/O cards, so I would start with those first. Replace each, one by one (power down first for each replacement). Make sure any dipswitch settings or jumpers are matched up.

Sometimes with lots of I/O, tracking down the culprit can take quite some time.

It might also be helpful to share the SLC program with us or at least the complete I/O listing.

 

[James Mcquade]

open your program and look in the project section on the left.
look in the Controller section
open the IO Configuration section.
your I/O will be defined there.
click on the power supply button.
change the power supply to the one in use and it will indicate if the
power supply is too small or iffy.
if it is to small, i would replace that first
regards,
james

 

[02js4130]

Thanks for the answers! The process has been running for a long time without issues so im confident that the spec of the PSU,CPU and its modules is correct. we replaced all of the 1746-IB16 and 1746-OW16 input and output cards as this is the only spares we had and it hasn't faulted as of yet. so need to set up in the back room and try to identify which is causing the issue .

 

[02js4130]

Rtfm

Thanks this is usually the best place to start!

 

[I_Automation]

When a SLC rack with an analog card start acting up the FIRST thing I replace is the analog card.


If that doesn't work then the power supply (or both at once if I don't want to know what the exact cause was.


Obviously after the 13 slot rack there's another 4, 7 or 10 slot expansion rack.