Re: [foxboro] PIDTAU & PID Tuning.

While I haven't messed with the PIDTAU in a few years, I do recall that it
worked as expected.  Regarding the movement in output when the SPT is
changed, this is governed by the SPLLAG parameter and also by the PB.  For
fast response to SPT changes there is an optimal value for SPLLAG.  If set
to 0.0 (No output bump) then changes to SPT will be much slower (Longer time
for MEAS to reach SPT) and the output will only change at the reset rate
(Integral tuning parameter).  Regarding the lack of output response with a
sustained error, this should not occur (i.e. Somethings wrong) as the
MODOPT=8 has P+I+D and the integral should eventually return the MEAS to
SPT.  Maybe you set the I to a very large value?, Maybe noise in the MEAS is
being acted on with the Derivative.  You can set the D to zero.  Also the
PIDTAU can be tuned with the FBTUNE block and the pretune function (bi-polar
pulse) usually gets the tuning values very close.

Regarding the managment of PID tuning in general there are some third party
packages out there that can keep track of/manage tuning settings.  You can
find these in google by searching "PID tuning".

Rick Rys




 
 
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