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David Nelson

slc 5/04 bit shift

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hello folks, i have a question as to whether or not a BSR would be appropriate for a load queue. what i have is a generator controled by a slc 5 04. the total load is roughly twice the size of the generator. so what i have come up with is using intergers and math instructions to calculate how much wattage is actually being used and how much is left and bring in other loads when one drops out that doent exceed the wattage thats left and hold off all other loads. could i use some type of bit shift to create a queue to sort of create a first come first serve type deal? timing is not critical so if one has to wait a while it is not a problem i just dont want the larger loads hogging the hole thing all the time i want to be fair and give everything a turn so to speak. if this sounds like it might work how would the rungs be written? thanks , david

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can't you just measure current and bring it to analog input? how many outputs (loads) we are talking about? is each load fixed (and known) or may eventualy change significantly?

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I feel that bit shift will not workout for this application

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I built something similiar to this in an Omron PLC using a crude bit shift years ago. We had a 20 to 1 merge conveyor and needed to give each feeder a 30 second feed oppourtunity out of each 10 minute window. If they where not ready when their turn came then they forfeited that time and the total cycle was reduced by 30 seconds. This drastically improved productivity over the previous first come first serve logic which favored stations closer to the exit of the system. Bottom line I think you can come up with code, but it will not be simple and you probably won't use the BSL or BSR instructions but will code a sequence of your own.

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sounds like you have dealt with this Bob, any tid bits on how to get started? never written anything close to this type logic i think if i had a small sample i could probably figure out how to go from there. thanks

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