Rievtech xLogic ELC Series User Manual page 171

1. A disturbance causes the PV to drop, as Dir is positioned upwards, AQ increases until PV corresponds
again to SP.
2. A disturbance causes the PV to drop, as Dir is positioned upwards, AQ decreases until PV
corresponds again to SP.
Dir is coordinated to the basic conduct of a control loop. The direction (dir) cannot be changed
during the term of the function. The change in Dir here is shown for the purposes of clarification.
3. As AQ is set to 0 by means of the input R, PV changes. This is based on the fact that PV increases,
which on account of Dir = upwards causes AQ to drop.
Description of Function
If the input A/M is set to 0, then the special function issues output AQ with the value that you set with
parameter Mq.
If the input A/M is set to 1, then automatic mode commences. As an integral sum the value Mq is adopted,
the controller function begins the calculations in accordance with the formulas given in Control and
regulate basics. The updated value PV is used to calculate in the formulas.
Updated value PV = (PV * gain) + offset
If the updated value PV = SP, then the special function does not change the value
of AQ.
Dir = upwards/+ (timing diagram numbers 1 and 3)
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