[foxboro] SPD_CAP SELECTION

List,


Using a CALC block, I am trying to develop logic for capacity/speed
selection of a compressor. What I am doing is as following:



BIO1 : SPEED SELECT FBK

BI02 :  LOCAL/REMOTE SELECTION FBK

BI03 : CAPACITY SELECT FBK

BI04 : SPEED/CAPACITY TOGGLE SIGNAL (OPERATOR ACTION)



STEP01 = CST

STEP02 = IN BI02

STEP03 = BIF 25 ; COMPRESSOR IS ON LOCAL DONOT DO ANYTHING

STEP04 = IN ~BI04 ; OPEARATOR NOT TOGGLE THE INPUT

STEP05 = IN BI03 ; CAPACITY SELECT FBK IS 1

STEP06 = AND 2

STEP07 = BIF 11 ; GO AND CHECK THE 2ND CONDITION

STEP08 = CLR BO01 ; SPEED TRACKING

STEP09 = SET BO02 ; CAPACITY SELECT

STEP10 =  GTO 27 ; GO TO END

STEP11 =  IN BI04 ; OPERATOR TOGGLE THE INPUT

STEP12 =  IN BI03 ; CAPACITY SELECT FBK IS 1

STEP13 =  AND 2

STEP14 = BIF 18 ; GO AND CHECK THE 3RD CONDITION

STEP15 = SET BO01 ; SPEED SELECT

STEP16 = CLR BO02 ; CAPACITY TRACKING

STEP17 = GOT 27 ;  GO TO END

STEP18 = IN BI04 ; OPERATOR TOGGLE THE INPUT

STEP19 = IN BI01 ; SPEED SELECT FBK IS 1

STEP20 = AND 2

STEP21 = BIF 27 ; NO COMMAND ISSUED GO TO END

STEP22 = CLR BO01 ; SPEED TRACKING

STEP23 = SET BO02 ; CAPACITY SELECT

STEP24 = GTO 27 ; GO TO END

STEP25 = CLR BO01; WHEN COMPRESSOR IS IN LOCAL BOTH SPEED AND

STEP26 = CLR BO02; CAPACITY WOULD TRACK ONLY

STEP27 = END



Is there better idea for doing the same? The logic is based on the
following:

   1. When compressor is on local both speed and capacity should track
   only (start-up).
   2. When compressor switched to remote capacity is default mode of
   control.
   3. When compressor is on capacity control and lost the capacity
   feedback (for any reason) there should be no change in status.
   4. When compressor is on speed control and lost the speed feedback
   (for any reason) there should be no change in status.
   5. If for any reason compressor switched over to local control, set
   both speed and capacity to track only.
   6. Speed or Capacity selection would be by operator request only.

 Regards,

Jalil Saeidzadeh

 
 
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