Re: [foxboro] ACCUM Block With Period = 8 (1 Hour)

I prefer using PCNTOP = 0 so it doesn't matter what the period is. It's the
same meter factor at any period. It separates the issue of the rate units
from the execution period, so the meter factor is simply a unit conversion.
The assumed rate for the MEAS is per minute, so if your measurement is per
hour, you'll have to use the MTRFAC to scale it to minutes (0.01666666667).
I'd make this change and then try different periods. They should all
provide the same answer after an hour.

Jerry Hidahl
Process Control Engineer
Port Neches Performance Products
Huntsman Corporation

Previous message by Tom Badura:

Terry and Greg,
I set the Meas input to the accum block at 1,000,000 and reset the
total.  The MRATE was then 277.78/sec - OK.  After 1 Hour the total was
89,777.8 - off by that same factor.
An OMGET of the PERTIM = 3600 as it should.

Again the parameters are:
PERIOD = 8 (1 Hour)
MTRFAC = 1
PCNTOP = 0
LSCI = 0
HSCI = 9999999
LSCO = 0
HSCO = 9999999

I can't think of anything else that should have an effect.


Tom Badura
Plastics Engineering Company

 
 
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