Re: [foxboro] a simple challenge


Michel,

In a PLB block, I don't believe that the times can be varied by external
means.  They are hard coded into the PLB logic.

A CALC block might be your best bet for something like this.
                                    
                                    
                                    




Stan M. Ruth, P.E.
Process Control Engineer
Huntsman O&O Plant

E-mail: stan_ruth@xxxxxxxxxxxx


                                                                                
                                     
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                    11/21/2001 02:24                                            
                                     
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Hi list,

We are going to replace a local relay / timer driven filter cleaning
sequence by "something" in I/A.
We therefore need to separately activate 4 solenoids, one after the oth=
er,
for a variable number of seconds (most likely 2). The interval between
activating the solenoids should also be variable.
I have already made something with a Calc block that generates seconds =
( 0
to 62) connected to a AIN block. On the four boolean alarm limits I
connected the solenoids using a GDEV with the pulse option on. But ther=
e
must be something more brilliant than this, without the use of a DEP bl=
ock.
The solenoids will be connected (2?wire) to FBM41C/42C, therefore a PLB=

solution is an option.
All suggestions are more than welcome.

thanks,

Michel




Michel van den Berg
PFW Aroma Chemicals B.V.
PO Box 415
3770 AK Barneveld
the Netherlands

Phone : (31)342 - 407 791
Fax   : (31)342 - 407 789
email : mvandenberg@xxxxxx
FedEx : Nijverheidsweg 60
        3771 ME Barneveld
        the Netherlands
=




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