SLC Errors

[lostcontrol]

Hi,

We recently had a SLC504 fault with Error code 857h. Now, from the help files, this means that it was in slot 8, with fault 57, which is:

A specialty I/O module has not responded to a lock shared memory command withing the required time limit. This error is recoverable.

And the error has been recovered, but is this a symptom of the module failing? What would be the best pland of attack to negate this happening again?

I have a suspicion that this has happened before recently, but did not have a copy of the error log, as thje fault was cleared with the key switch before we were aware of it.

 

[JeffKiper]

What is the card in slot 8? I have seem problems out of the backplanr on SLC before.

 

[lostcontrol]

Analogue Module, NI4 I think. This install is of reasonable age, and probably not the best quality, IMO anyway...

 

[JeffKiper]

has anybody made any changes to the system lately? I ASSuMEd tha no-one had but I didn't ask.
Do you have a spare Analog card to play swaptronics with? Swap them out and see if the problem follows. Yea I know that is not exact answer that you where hoping for. Spare rack?

 

[Mickey]

It can't hurt to power down and pull the card, shine up the contacts and reseat it.
An eraser works well for this.

 

[OkiePC]

And, while you're re-seating cards, check your chassis ground and physical mounting. There should be a good ground to the chassis and power supply. I suspect noise as much as a failing card in this case. The symptoms sound like noise tripped up the A/D CPU, moreso than the rack couldn't find the card type faults. This noise is more likely to have come into the signal wiring than the the backplane. I have seen it more with RTD inputs, and voltage i/o than current though. ie. shield drain breaks open, then we get noise on the signal and two or three faults before it's found. Make sure your analog cabling is segregated from VFD power leads, and insulation and shielding is not compromised.

We have 14 SLCs in high heat high vibration enclosures and the little plastic locking tabs occasionally unlock from all hte shaking and cause the hardware slot fault.

About 2% of the faults I have seen where there was a bad backplane electrical open or short, the SLC would either fail to identify the slot number or report it incorrectly.

If the fault re-occurs, of course, swap it with a spare if available to rule that out, but be aware of the periphery if it comes back at ya' on a fresh card.

SLC cards are surprisingly tough! Once they're dead, they usually stay dead, though.

 

[Marc_U]

About 2% of the faults I have seen where there was a bad backplane electrical open or short, the SLC would either fail to identify the slot number or report it incorrectly.

If the fault re-occurs, of course, swap it with a spare if available to rule that out, but be aware of the periphery if it comes back at ya' on a fresh card.

SLC cards are surprisingly tough! Once they're dead, they usually stay dead, though.

Just to agree with Okie. It is very possible that it may be a different card in another slot that has gone down, & has possibly partly shorting out one of the backplate voltage supplies, or something. This can lead the CPU to mis-identify which is the faulty module/slot.

So if the fault is still there after you have replaced the module, take a close look at the other slots. For as Okie says once an SLC card is dead, it stays dead.