Re: [foxboro] Foxboro Control Philosophy 101

As long as there is sufficeint documentation , if works , it's good.

-----Original Message-----
From: Gregory A Hurwitt [mailto:hurwitg@xxxxxxxxxxxxx]
Sent: Monday, October 29, 2001 8:32 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Foxboro Control Philosophy 101



As someone with a little programming experience, I like the elegance of the
KSCALE solution.  However, I don't think that you should expect the intent
of
this "hack" to be immediately obvious to your E&I techs.  The connection of
a
boolean signal to a parameter that's intended to take an analog value will
be
confusing to many.

Greg Hurwitt
Staff I/E Engineer
BASF Corp./Freeport, TX





David Johnson <djohnson@xxxxxxxxxxxxx> on 10/25/2001 05:12:49 PM

Please respond to foxboro@xxxxxxxxxxxxx
To:   foxboro
cc:
Subject:  [foxboro] Foxboro Control Philosophy 101






I have a flow transmitter (AIN) that gives strange readings when no flow,
or a reversed flow, is going through the pipe.  The motor that drives the
pump is controlled via an AB PLC and the aux. contact of the motor is
available to I/A from an existing I/A gateway (CIN).  When the motor is off
I would like to force the AIN to output a 0.


[snip]

3) A non-obvious answer
Connect the CIN.CIN to the AIN.KSCALE.  When the motor is on, the AIN.PNT
sends the correct data, when the motor is off you get a 0.

Advantages over method 1 and 2
Very tight, no additional blocks, works great.

Disadvantages over method 1 and 2
It hides the fact that you intend to zero the output when the motor is off.
In fact using a parameter like KSCALE for zeroing output is easily
overlooked.

I am sure there are other ways to solve the problem (maybe we should have a
contest).  BUT, what I am trying to determine from some of you old timers
is, are clever and efficient use of block resources worth the possible
downside in troubleshooting.  OR, should any reasonably competent E&I tech
be able to immediately identify a KSCALE hack and troubleshooting is not an
issue in this case.  I value any insights you might have.








 
 
___________________________________________________________________
This list is neither sponsored nor endorsed by The Foxboro Company.
Use the information obtained here at your own risk. For disclaimer,
see http://www.thecassandraproject.org/disclaimer.html#maillist

list info:   http://www.freelists.org/list/foxboro
subscribe:   mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave


 
 
___________________________________________________________________
This list is neither sponsored nor endorsed by The Foxboro Company.
Use the information obtained here at your own risk. For disclaimer,
see http://www.thecassandraproject.org/disclaimer.html#maillist

list info:   http://www.freelists.org/list/foxboro
subscribe:   mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave

Other related posts: