sajidnasir

Silo Filling on First Demand First Fill Sequence

3 posts in this topic

Hi All!

Can anyone help me regarding the following logic:

1. I have four Silos and one filling station.

2. The filling of silos starts on the bases of silo demad (i.e demand is a digital signal that comes when silo is empty)

3. I have to fill all silos according to their demand

4. Whose demand is first that is filled first

5. for e.g if all four silos are empty they all generate a demand signal.

6. If Filling of silo 1 is done and filling is in progress at silo 2 after that filling will start  in silo 3 then silo 4 as they are empty

7. In the mean time  if silo 1 empy again and filling is in progress at silo 2. The system must fill silo 3 and 4 first then go to silo 1 

8. It means which demands first that is filled first (first come first serve) 

 

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You didn't mention which platform you're using, but I would use a FIFO stack. That's "First In - First Out". Some PLCs have FIFO instructions built in, which makes it easy. To write your own, you would basically create an array large enough to hold the maximum number of empty requests that can happen simultaneously. With 4 silos, that would be minimum 4 elements. I would make it larger, just to allow for future expansion. You'll also need an index tag. If there aren't any empty requests, the index value will be 0 and the FIFO array will be empty. Whichever silo is empty first, store that number in array element 0 and add one to the index register. The next silo's number will be stored in array element 1, and so on, with each request going into FIFO_Array[index]. Your fill system will fill up whichever silo's number is in FIFO_Array[0]. Once that silo is full, you move FIFO_Array[1] into FIFO_Array[0], FIFO_Array[2] into ...[1], etc., and subtract 1 from the index. Once the index = 0 again, none of the silos are empty.

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Dear Mr Joe E

I am using Fatek Plc.

you have explained it very well. Now i will try to develop the logic.

Thankyou so much for you assistance 

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