Pid Overview; Feedback Handling - Danfoss VLT 6000 series Operating Instructions Manual

PID overview

The block diagram below shows reference and
setpoint in relation to the feedback signal.
As can be seen, the remote reference is totalled
with setpoint 1 or setpoint 2. See also Reference
handling. Which setpoint is to be totalled with the

Feedback handling

The feedback handling can be seen from the
block diagram on the next page.
The block diagram shows how and by which
parameters the feedback handling can be affected.
Options as feedback signals are: voltage, current,
pulse and bus feedback signals. In zone regulation,
feedback signals must be selected as voltage inputs
(terminals 53 and 54). Please note that Feedback 1
consists of bus feedback 1 (parameter 535) totalled
with the feedback signal value of terminal 53. Feedback
2 consists of bus feedback 2 (parameter 536) totalled
with the feedback signal value of terminal 54.
In addition, the frequency converter has an integral
calculator capable of converting a pressure signal
into a "linear flow" feedback signal. This function is
activated in parameter 416 Feedback conversion.
The parameters for feedback handling are active both
in closed and open loop modes. In open loop, the
present temperature can be displayed by connecting
a temperature transmitter to a feedback input.
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.61.A5.02 - VLT is a registered Danfoss trademark
®
VLT 6000 HVAC Series
remote reference depends on the selection made
in parameter 417 Feedback function.
In a closed loop, there are - roughly speaking -
three possibilities of using the integral PID regulator
and set-point/ feedback handling:
1. 1 setpoint and 1 feedback
2. 1 setpoint and 2 feedbacks
3. 2 Setpoints and 2 feedbacks
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