Re: [foxboro] Global Variable Connections

OK.  How about a related issue.

At a customer site there are 2 CP60s.  A CALCA in one CP executes
some logic which uses a Boolean input sourced from a CIN to the other
CP.

When the connection from the CALCA Boolean input is first made
to the CIN in the other CP, it will not resolve until the source
value changes state (we have been thru checkpoints, yes).  Further
work shows that that this also happens with other Boolean
connections, and may occur with real values in some cases as well.

This particular application involves boilers, and the signal is a 
boiler purge signal; it can not be toggled while the process is up
unless several other blocks are put to manual, and operations
doesn't like that.

What we did as to put a second CIN block in the same CP with the 
Purge signal's CIN to repeat the Purge signal.  We connect the CALCA
to that second CIN and it can be put into Manual and toggled to 
show us the connection is OK, then put in Auto for operation.  That
solves the immediate problem.
 
The base problem remains.  Any suggestions for a better work-around
than adding a bunch of otherwise superfluous blocks ??

William C Ricker
FeedForward, Inc.
 


 
 
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