Re: [foxboro] Motor Start/Stop Logic

List,
        Thanks to all that responded.  There were many interesting
solutions but it is interesting to note that neither the GDEV nor MOTOR
blocks provide everything that is needed to Start and Stop Motors
without additional logic blocks or field wiring retrofit.  Here is an
opportunity for improvement Foxboro!  The GDEV's pulse option on the
Start, (COUT_1), correctly mimics the momentary Start button installed
on most field operated motors.  The Stop, (COUT_2), contact is usually a
maintained switch in the field but pulsing it open for 6 seconds from
the GDEV block is good enough to insure that the contactor drops out.
The only thing the GDEV and MOTOR blocks don't do like a regular field
motor, is to seal in, (MAINTAIN), the Run/Start Contact once the run
status is confirmed with feedback from the motor starter.  If it did
that none of us would need the following Logic Block that we built to
perform that operation.
        This block does exactly what we want for all of our DCS
controlled motors as long as we use the PULSED output option in the GDEV
block.  It is placed between the GDEV block's COUT_1 and the "START"
COUT block.  BO01 is sent to the COUT's .IN parameter, but it would be
much simpler if I could send the .COUT_1 of the GDEV directly to the
START COUT block.
Cheers,
Tom VandeWater

  NAME   LOGIC20326
  TYPE   LOGIC
  DESCRP MOTOR LATCH RESET TEST
  PERIOD 1
  PHASE  0
  LOOPID
  BI01   :MTR20326.COUT_1       (GDEV START PULSE)
  BI02   :MTR20326.COUT_2       (GDEV STOP PULSE)
  BI03   :YI20326.CIN         (MOTOR RUN STATUS)
  STEP01 CST
  STEP02 IN BI02    ; CHECK FOR STOP PULSE
  STEP03 BIF 14     ; IF STOP CLEAR COUT
  STEP04 NOP        ;
  STEP05 IN BI01    ; CHECK FOR START PULSE
  STEP06 BIT 12     ; IF START SET COUT
  STEP07 NOP        ;
  STEP08 IN BI03    ; CHECK RUN STATUS
  STEP09 BIF 14     ; IF NOT RUNNING CLEAR COUT
  STEP10 EXIT       ;
  STEP11 NOP        ;
  STEP12 SET BO01   ; LATCH START
  STEP13 EXIT       ;
  STEP14 CLR BO01   ; SEND STOP TO COUT BLK
  STEP15 END        ;

 
 
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