GE VersaMax PLC User Manual page 278

Words
12
Minimum Slew Time
(Address + 11)
Minimum number of seconds for the CV output to move from
0 to full travel of 100% or 32000 CV Counts. It is an inverse
rate limit on how fast the CV output can change.
If positive, CV cannot change more than 32000 CV Counts
times the solution time interval (seconds) divided by Minimum
Slew Time.
For example, if the Sample Period is 2.5 seconds and the
Minimum Slew Time is 500 seconds, CV cannot change more
than 32000 * 2.5 / 500 or 160 CV Counts per PID solution.
The integral term value is adjusted if the CV rate limit is
exceeded.
When Minimum Slew Time is 0, there is no CV rate limit. Set
Minimum Slew Time to 0 while tuning or adjusting PID loop
gains.
13 Config Word
(Address + 12) The low 6 bits of this word are used to modify default PID
settings. The other bits should be set to 0.
Bit 0: Error Term Mode. When this bit is 0, the error term is SP
- PV. When this bit is 1, the error term is PV - SP. Setting this
bit to 1 modifies the standard PID Error Term from the normal
(SP – PV) to (PV – SP), reversing the sign of the feedback
term. This mode is used for reverse acting controls where the
CV must go down when the PV goes up.
Bit 1: Output Polarity. When this bit is 0, the CV output is the
output of the PID calculation. When it is set to 1, the CV
output is the negated output of the PID calculation. Setting
this bit to 1 inverts the Output Polarity so that CV is the
negative of the PID output rather than the normal positive
value.
Bit 2: Derivative action on PV. When this bit is 0, the
derivative action is applied to the error term. When it is set to
1, the derivative action is applied to PV only.
Bit 3: Deadband action. When the Deadband action bit is 0,
the actual error value is used for the PID calculation. When
the Deadband action bit is 1, deadband action is chosen. If
the error value is within the deadband limits, the error used for
the PID calculation is forced to be zero. If, however, the error
value is outside the deadband limits, the magnitude of the
error used for the PID calculation is reduced by the deadband
limit (|error| = |error – deadband limit|).
278 GFK-1503E
For public disclosure
Parameter/Description Low Bit Range
Units
Seconds / Full 0 (none) to 32000 sec
Travel to move full CV travel
VersaMax PLC User Manual