PID Parameters

Mixed or Parallel Structure

If the loop controller structure is mixed (default configuration), the proportional action is applied downstream of the integral and derivative actions. The K gain applied to these actions is therefore equal to kp.
If the loop controller structure is parallel, the proportional action is applied parallel to the integral and derivative actions. In this case the kp gain is not applied to the integral and derivative actions. The K gain is simply equal to the relation between the output scale and the process value scale.

Direct or Inverse Action

The direction of the PID Loop Controller may be adapted to that of the actuator/process pair. The action can be defined in the opposite direction (default configuration) or in the same direction.

If the action is direct, a positive gap (PV – SP) leads to an output increase.

If the action is inverse a positive gap (PV – SP) leads to an output decrease.

Derivative Action

The derivative action can act upon the process value or the gap.

Manual / Auto Switching

The absolute form of the algorithm allows Manu / Auto switching without bumps.

Adjustment Parameters

Internal Parameters:

Parameter	Symbol	Type	Thresholds	Default Value	R/W
Lower limit of the process value scale	PV_INF	REAL	-3.4E38 / 3.4E38	0.0	R/W
Upper limit of process value scale	PV_SUP	REAL	-3.4E38 / 3.4E38	100.0	R/W
Lower limit of output scale	OUT_INF	REAL	-3.4E38 / 3.4E38	0.0	R/W
Upper limit of output scale	OUT_SUP	REAL	-3.4E38 / 3.4E38	100.0	R/W
Proportional gain	KP	REAL	0.0 / 3.4E38	1.0	R/W
Integration time (s)	TI	REAL	0.0 / 3.4E38	0.0	R/W
Derivation time (s)	TD	REAL	0.0 / 3.4E38	0.0	R/W
Derivative gain	KD	REAL	1,0 / 3.4E38	10.0	R/W
Dead band on deviation	DBAND	REAL	0.0 / 3.4E38	0.0	R/W
Manual compensation of the static gap	OUTBIAS	REAL	-3.4E38 / 3.4E38	0.0	R/W
Limiting the output variation, in units s	OUTRATE	REAL	0.0 / 3.4E38	0.0	R/W
Integral band	INT_BAND	REAL	0.0 / 3.4E38	0.0	R/W

Dead band on deviation

The dead band on deviation (DBAND) is used to limit small recovery bumps to actuator to the function point. As long as the gap remains smaller than DBAND (in absolute value), the loop controller assumes it to be null for its calculations.

Integral Band

The integral band defines a zone (around the setpoint) in which the integral action is calculated. When the process value / setpoint gap is greater than this band the integral action is frozen.

The integral band is limited to the proportional band (100 / Kp).

BIAS on the Command

If the integral action is not used (Ti = 0), the use of BIAS on the PID command (OUTBIAS), is used to guarantee precision of the function point.

If Ti is different from 0, OUTBIAS is not taken into account.