Goofy AOI Label Tamper Logic

Been in the digital world half my life, but only recently in PLCs. I inherited a Tamper project from 5 years back which never worked. Tamper is s'posed to put a label on any Manual Sort box, and ignore those which have a good routing destination. All boxes get a good Product Detect Photo Eye signal. Logic is s'posed to clear the PD bit, following the start of the Manual Sort Tamp Cycle, if next the box has a good destination. Problem is, we get from one to three additional tamps on good boxes following the Manual Sort box. The associated AOIs are way overbuilt for this logic, and were dropped in place and band-aided together by the original vendor. Makes them hard to troubleshoot and/or modify. Half the rungs don't even execute.



Rung 5 - Valid Package at Photo Eye has back to back OSR/OSF functions. However, it never fires. Also, the PE Clear above never fires. I understand the need for debounce, but this looks like it would give me a one machine cycle positive pulse. Is that OK? Any ideas... TIA

I'm not sure exactly what is going on, but it is that 1-shot logic that is giving you your problems. Can you post up a pic of the tamping line so we can see what is happening and perhaps the entire project to take a gander at?


At first glance, the OSR to OSF seems to be a problem here. For whatever reason, you are tamping three times, which means that during what should be a single cycle, that tamper is tamping, resetting, then tamping again the entire time your box is in that position. Rung 5 seems to be where you want to start here. I would also keep an eye on the Val_PkgAtPhotoEye while the system is running. See if it is resetting during this time frame.

EDIT: I just reread your post. Just because you don't see it change on screen does NOT mean that it isn't firing and giving a pulse to the program.

What I would do to troubleshoot is XIC the PE_Cleared bit and count up a counter or ADD 1 to a DINT. That way you could see if it is going high once in a while.

Do this with the other OneShots as well. Also, and a branch on the output of line 5 with an ADD or counter to see if that line does get true, and how often the value increments.

Goofy AOI Workaround

Thanks, guys! Your feedback was quite helpful. Here is my workaround code. It runs, but still has a couple of problems:



1) Rung 4 is letting slivers through, and my Tamp Counter at the bottom increments up. I am looking for a Manual Sort = TRUE coincident with the PKG Detect, to generate a Label Tamp on the detected carton.



2) The tamper is putting labels on Decant and Prep cartons, but is missing the Manual Sort cartons.



The Happy Path cartons go right through with no issues (no label).



Again, I think the problem is Rung 4. The EQU/NEQ statements are getting Lane Map, and Routing Telegram info from the Shipping Server (AOIs elsewhere).



Those AOIs have been working perfectly for years with our Primary Tamper (applies bar code labels). However, my Manual Sort Tamper is 100 feet downstream (30 seconds delayed) from the primary.


So wondering if I need to create a Moving Pkg Zone Window, to keep the Telegram info synced up with the moving carton (or hopefully find that function somewhere in the existing AOIs).


Your Thoughts?

Can anyone advise as to how to...

Filter spikes coming through Rung 4?

Should I run a

FB Low Pass Filter, or simply skip any triggers which are shorter than 5-10ms?