Operating Instructions

Appendix A: Parameter Reference List
Siemens Building Technologies, Inc. 169
Dependency: If P term=0, I term acts on the square of the error signal.
Note: If the system is prone to sudden step changes in the feedback signal, P term should normally be set to a small
value (0.5) with a faster I term for optimum performance.
The D term (P2274) multiplies the difference between the present and previous feedback signal thus accelerating
the controller reaction to an error that appears suddenly.
The D term should be used carefully, since it can cause the controller output to fluctuate as every change in the
feedback signal is amplified by the controller derivative action.
P2285 PID integral time
Min: 0.000 Def: 0.000 Max: 60.000
Level 2
Note: See P2280 (PID proportional gain).
P2291 PID output upper limit
Min: -200.00 Def: 100.00 Max: 200.00
Level 2
Dependency: If F max (P1082) is greater than P2000 (reference frequency), either P2000 or P2291 (PID output upper limit)
must be changed to achieve F max.
Note: P2291=100% corresponds to 4000 hex (as defined by P2000 [reference frequency] ).
P2292 PID output lower limit
Min: -200.00 Def: 0.00 Max: 200.00
Level 2
Dependency: A negative value allows bipolar operation of PID controller.
Note: P2292=100% corresponds to 4000 hex.
P2293 Ramp up/-down time of PID limit
Min: 0.00 Def: 0.00 Max: 100.00
Level 3
Detail: Sets maximum ramp rate on output of PID. When PI is enabled, the output limits are ramped up from 0 to the
limits set in P2291 (PID output upper limit ) and P2292 (PID output lower limit). Limits prevent large setup changes
appearing on the output of the PID when the VFD is started. Once the limits have been reached, the PID controller
output is instantaneous. These ramp times are used whenever a Run command is issued.
Note: If an OFF1 or OFF3 are issued, the VFD output frequency ramps down as set in P1121 (ramp-down time) or
P1135 (ramp=down time).
r2294 CO: Act. PID output
Min: - Def: - Max: -
Level 2
Note: r2294=100% corresponds to 4000 hex.
P2303[2] CI: PID o/p offset
Min: 0:0 Def: 0.0 Max: 4000.0
Level 3
Settings: 755=Analog input 1 setpoint 2224=Fixed PID setpoint 2250=Output setpoint of PID-MOP
Index: P2303[0]= IN000 (AUTO) 1st command data set (CDS) P2303[1]= IN001 (HAND) 2nd command data set
(CDS)
Note: On selection of an analog input, offset and gain can be implemented using parameters