Dwyer 32DZ - Manual (Page 12)

949-1318 Page 12 of 40 June, 2000
OPERATION OF SELF TUNE® FUNCTION
Self Tune® allows automatic selection of the necessary parameters to
achieve best control operation from your 32DZ Series control. If you are
using the control output as a simple on-off function (e.g.
Out1 Out1 Out1 Out1 Out1 set for OnOF OnOF OnOF OnOF OnOF ),
none of the following will apply.
Theory of Operation
The Self Tune function calculates the Pb1 Pb1 Pb1 Pb1 Pb1 , rES1 rES1 rES1 rES1 rES1 , and rtE1 rtE1 rtE1 rtE1 rtE1 parameters under
the PID1 tunE PID1 tunE PID1 tunE PID1 tunE PID1 tunE selection, Pb2 Pb2 Pb2 Pb2 Pb2 , rES2 rES2 rES2 rES2 rES2 , and rtE2 rtE2 rtE2 rtE2 rtE2 parameters under the PID2 tunE PID2 tunE PID2 tunE PID2 tunE PID2 tunE
selection, the Fbd1 Fbd1 Fbd1 Fbd1 Fbd1 and Frt1 Frt1 Frt1 Frt1 Frt1 parameters, and the Fbd2 Fbd2 Fbd2 Fbd2 Fbd2 and Frt2 Frt2 Frt2 Frt2 Frt2 parameters,
as shown in the Secondary Menu . These values are determined by measuring
the response of the process connected to the control. When Self Tune is
started, the control temporarily acts as an on-off control. While in this mode
the control measures the overshoot and undershoot of the process, and the
period of the process (the time from peak value to the next peak value). These
measurements are collected over a period that lasts three periods of overshoot
and undershoot. The data collected over this time is then compared and
calculated into final PID and Fuzzy Logic values. The effect of Fuzzy Logic
on the process is still controlled by the
Fi 1 Fi 1 Fi 1 Fi 1 Fi 1 and Fi 2 (fuzzy intensity) settings.
If Fi 1 Fi 1 Fi 1 Fi 1 Fi 1 or Fi 2 is 0 00 00 , the Fbd1 Fbd1 Fbd1 Fbd1 Fbd1 , Frt1 Frt1 Frt1 Frt1 Frt1 , Fbd2 Fbd2 Fbd2 Fbd2 Fbd2 , and Frt2 Frt2 Frt2 Frt2 Frt2 will be calculated, but will
have no effect.
The calculations for Zone 1 and Zone 2 are completely independent. Each zone
has separate Self Tune and Fuzzy Logic parameters.
Set Point 2 Tracking
Some applications will call for Set Point 2 to follow or 'track' the setting for
Set Point 1. This can be done by changing the
S2t setting in the Secure Menu
( edit set for 2 or 3 ). For a tracking SP2 , set S2t to dE .
The Factory Default setting for S2t is ABS , making SP2 completely
independent of SP1 .
When setting SP2 SP2 SP2 SP2 SP2 value when Set Point 2 is programmed as deviation ( S2t S2t S2t S2t S2t
= dE dE dE dE dE ), set the difference in value from the Set Point 1 ( SP1 SP1 SP1 SP1 SP1 ) desired. For
example if Set Point 2 is required to be 5 degrees below the SP1 SP1 SP1 SP1 SP1 , then set
SP2 SP2 SP2 SP2 SP2 to -5 -5 -5 -5 -5 . If Set Point 2 is required 20 degrees above the SP1 SP1 SP1 SP1 SP1 , then set SP2 SP2 SP2 SP2 SP2
to 20 20 20 20 20 . If SP1 SP1 SP1 SP1 SP1 is changed, the SP2 SP2 SP2 SP2 SP2 setting will continue to hold the same
relationship as originally set.
When setting SP2 value when Set Point 2 is programmed as absolute (S2t
= AbS), simply set the value at which the alarm is to occur.