Light Curtain Muting Instruction Help

Ok all, I'd appreciate any and all help understanding this -

Lately I have been having some trouble with a discharge light curtain on one of our palletizers. I *suspect* it may be due to a reflective style photoeye reflecting off of a film-wrapped product or a very glossy package. The light curtain in question gives an input to a 1769-ERMS Compact Guardlogix controller, utilized by an FSBM instruction. I have tried using a MOV instruction to grab the fault code and copy it to another tag after it happens (Operators around here like to clear things quickly, go figure) so I can look up what it means but the code I am getting is nowhere to be found in the instruction help. First time I was able to get '37376', and just a minute ago I got '37396'. What the heck does it mean? Do I have a lack of an underlying understanding of the operation/instruction?

Ok I think I figured it out on my own...

For all who may be interested, or want to correct me (feel free)...

The values I was getting were in a decimal format. The fault codes in the instruction help are followed by an 'H', which I believe stands for Hex. Converting my decimal value of '37396' to a Hexadecimal value gives me a value of '9214'. Slap an 'H' on the end of that and we have ourselves a legit fault code in the help section.


Math.....:angr:


P.S. That fault is all 4 PE's are clear but the curtain is still blocked.... new theory: PE's too low/Seeing through pallet.

Yep, that'll do it every time. Most fault codes are in hex, no idea why. Probably a hangover from early computing days when hex was all the rage.

Most muting sensors I see are emitter-receiver type, to prevent false reflections like you initially suspected. If they're seeing under the pallet, well, can't help you there - but an emitter/receiver will certainly help if all four sensors think they're clear because they're reflecting off the wrapping. If you think about it, that's how the PLC knows there's a fault - because the reflective sensors (PE's) think they're clear, but the emitter/receiver sensor (light curtain) insists that it isn't.