RSLogix5000 Dual Check Input Stop Fault 32

[rockemsockem]

Hi,
I have 2 safety devices (Banner EZ LS light curtains and a Keyence GS-71 Interlock) that are giving me some difficulties. The plc is a Compact GuardLogix, with a 5069-IB8S input module. The safety program uses the DCS instruction for the e-stop, light curtains, and interlock. During operation, the DCS for the light curtains and for the interlock both post fault 32 (inputs changed state during execution of instruction).

From what I can tell, the OSSD outputs for the light curtains and interlock are pulsing as part of a self-testing procedure, which is what's causing the fault 32. If you know a way off-hand to stop that or account for it in the DCS instruction, how can I do that? If that could compromise the safety rating, what would be the proper way to program the safety controls for these devices?

 

[I_Automation]

Couldn't you simply have the light curtain 2 channel output trigger a Banner safety relay or 2 interposing relays?


If not a safety relay for redundancy use 2 separate relays and loop the signal through 2 N.O. contacts on each.


The relays will not pulse with the output and the PLC will get a smooth signal from the relays.

 

[DarrylR]

Adjust the Discrepancy time?

 

[rockemsockem]

I was hoping to not have to add additional hardware, but if that is the proper way to do it, then that's the proper way to do it.




The discrepancy time is set to 200ms already, which is quite a bit more than the pulse time. If you think increasing it more will help I can certainly try but I am not sure it will.

 

[plvlce]

Do you have the LC (Light Curtain) instruction available on your controller? It has software input filtering available for just this purpose.

EDIT: See https://literature.rockwellautomati...re/documents/rm/1756-rm095_-en-p.pdf#page=481

 

[rockemsockem]

Do you have the LC (Light Curtain) instruction available on your controller? It has software input filtering available for just this purpose.

EDIT: See https://literature.rockwellautomati...re/documents/rm/1756-rm095_-en-p.pdf#page=481

It does! Thank you very much, I'll be testing that out and will update the thread once I do.

 

[rockemsockem]

Ok so I ended up not using the LC instruction. I read through the help page for the LC instruction and it stated that a hardware solution is preferred. Specifically, the input module has filtering capabilities for each input terminal, and that is the preferred way to do it (according to the page anyways). I set the input module to filter drops less than 1 ms on the relevant points and that seems to have worked fine. Thank you for the help everyone!