Installation manual

Control Parameters
900M050U00  Athena Controls, Inc. 8-5
8.3 Configuring Control Parameters for PID Control
8.3.1 Introduction
When Proportional-Integral-Derivative (PID) control is used, the controller modulates
output power by adjusting the output power percentage within a proportional band.
Power is proportionally reduced as the process temperature gets closer to the setpoint
temperature. The integral action affects the output based on the duration of the process
value’s variation from the setpoint, and the derivative action affects the output based on
the rate of change of the process value.
The values of the PID tuning parameters are automatically adjusted during the Autotune
procedure (see 16.2).
Unless you want to tune the controller manually as described in 16.3, do not alter the
tuning parameters Proportional Band for Output 1, Proportional Band for Output 2,
Derivative (Rate) Action, and Integral Action (Auto Reset). If you enter a non-zero value
for the manual offset, the controller will ignore it when you do Autotune. The controller
uses only one reset, either auto or manual.
8.3.2 Specifying the Proportional Band for Manual Tuning of PID Control
Parameter Name
: Proportional Band for Output 1 (22) and Proportional Band
for Output 2 (23)
Name as Displayed:
Pb.1Pb.1 and Pb.2Pb.2
Used By:
all controllers
When Displayed:
if output 1 or output 2 type is PID; if both output 1 and output 2
are direct acting or reverse acting, then only Pb.1Pb.1 is displayed
and applied to both outputs.
Range:
RTD and thermocouple input types: 0.6 to sensor span
linear input types: 1 to value of the SCL.HSCL.H parameter in the InPInP
(input) menu. (See Note 1 below.)
Default:
100
Description:
Used to specify the width of the band above (direct-acting
outputs) or below (reverse-acting outputs) the setpoint within
which the controller will modulate the output as the process
value approaches the setpoint.
Note 1: The range is reduced when a linear input is used and the value of the dSPLdSPL
(display) menu dEC.PdEC.P (decimal position) parameter is not 0 (zero). See 4.3.2 for more
information about the effect of a linear input on numerical ranges.