Re: [foxboro] GDEV functionality - was Foxboro's programming

A GDEV block is designed to control one device - a valve, motor, pump or 
anything digital with two distinct states (opne/close, on/off).
   
  MANDRS/AUTDSR is the manual/auto command to drive the device.  The HOLD, 
INTERLOCK features are very desirable options. The MISMATCH indicators are nice 
for diagnostic and error handling.
   
  I am sold on this.  Try it you may like it.
   
  J. Wu
brad.s.wilson@xxxxxxxxxxxxxx wrote:
  OK, I've never had the security coding kick in before ... here's try #2.

Replying to Joseph Wu's note that GDEV provides independent outputs ... the
2 GDEV outputs, COUT_1 & COUT_2, are NOT independent.

There are (potentially) 4 output states for a GDEV ... both COUTs on, both
COUTs off, or each COUT on while the other is off. However, the GDEV only
allows for 2 desired states ... MANDSR/AUTDSR = 0 or 1.

With PLSOPT = 0, the 2 outputs are always opposite to each other (unless
INVCO is set).
With PLSOPT = 1, the 2 outputs are momentarily the same during stroking,
but it's not a permanent state.

Because INVCO1 & INVCO2 are non-connectable & non-settable, they cannot be
used to modify either scheme.

Has Foxboro ever considered making COUT_1 & COUT_2 truly independent, so
the GDEV could have 4 output states ?

Brad Wilson
Process Control Engineer
ExxonMobil Chemical Co
Edison Synthetics Plant
732-321-6115
732-321-6177 fax
Brad.S.Wilson@xxxxxxxxxxxxxx



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