Palletizer PLC conversion

junkerjorg

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Join Date
Nov 2007
Location
Wisconsin
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56
Has anyone converted an SLC to CompactLogix for an Alvey 910 palletizer? The translation went ok but there is some funky code around how they store and retrieve pattern data that has me scratching my head. In the old SLC they used word level indirect addressing, which you can't do in a CLX. I created a two dimensional array to deal with that but data isn't populating. But the way the code is written, it doesn't jump into the pattern routine until a change is made and then it writes the current data into a storage array before it retrieves the same data to write back to the working registers. I'm also a little unclear how the INT to DINT conversion in the SQO and MVM affects the data. I'm in panic mode because I am running out of time to get this complete and installed. :unsure:
 
Those conversion program never works 100%. I hate to say it but there's no short cut sometime, you just have to dig in and sort out the bad conversion one at a time.

You can always convert any DINT back to INT to minimize the confusion. You can post the few rungs of the problem area and we can help but it's not going to be a fun process. We can help but I would ask for someone familiar with Contrologix programming structure locally to give you a hand.
 
Those conversion program never works 100%. I hate to say it but there's no short cut sometime, you just have to dig in and sort out the bad conversion one at a time.

You can always convert any DINT back to INT to minimize the confusion. You can post the few rungs of the problem area and we can help but it's not going to be a fun process. We can help but I would ask for someone familiar with Contrologix programming structure locally to give you a hand.

Thanks man, I actually finally sorted out the pattern data and have it all storing and retrieving properly. My next issue is the actual working data. The INT's are writing to DINT's that are being used in the SQO. The SQO can't use INT's so I need to figure out how to get the data to line up. There an easy way to convert the INT's to DINT's? I've actually never had to do that oddly enough.
 
To be a little more clear, is there a way to get 50 INT's mapped into 50 DINT's and have the DINT match the INT bit for bit on the first 16 bits of the word?
 
You can use the MOV instruction to move an INT to a DINT tag. The MOV moves the value so the bit pattern should be the same, except for the sign bit.
 
Last edited:
You can use the MOV instruction to move an INT to a DINT tag. The MOV moves the value so the bit pattern should be the same, except for the sign bit.

Thanks Ken. My issue was I needed to copy 50 INTs into 50 DINTs. I ended up creating a loop to MOV all 50 elements with one MOV. But, based on odd or even layer I had to MOV different elements for the right layer. I'm attaching a couple of pics of the code. Anyone see a problem with doing it this way? I assume loop update time shouldn't be an issue.

Loop.PNG copy.PNG
 
I have done a loop with a label and jump before, it will increase scan time make sure to take note with the program monitor when looping to avoid the watch dog fault.

Can you do this in ST or do a single move per scan?
 

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