PID overview
The block diagram below shows reference and set-
point 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 remote refer-
ence depends on the selection made in parameter 417
Feedback function.
Feedback handling
The feedback handling can be seen from the block di-
agram on the next page.
The block diagram shows how and by which parame-
ters 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 feed-
back 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 activa-
ted 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.
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
VLT
®
6000 HVAC Series
= factory setting, () = display text, [] = value for use in communication via serial communication port
148 MG.61.B5.02 - VLT
®
is a registered Danfoss trademark
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