12
Configuration and Programming
4.6
PID Control
PID control mode is required for Ramp and Soak applications or for finer process control. For Mechanical
Relay and SSR outputs, the output will be on a percentage of time based on the PID control values. The
frequency of switching is determined by the (
CyCL
) parameter for each output.
For the optional analog output, the PID control changes the output to a percentage of the full scale
selected in the (RNGE) menu.
The SSR is synchronous and can only switch ON or OFF at the 0V AC.
PID mode may cause relay chattering when used with
StR.1
. For this reason, the cycle
time for
StR.1
is limited to a minimum of 1 second.
4.6.1
PID Configuration (PRoG > PId.S)
The PID tuning parameters must be set before PID control can be used. These parameters can
either be set by hand in the (
PRoG>PId.S>GAIN
) menu or the controller can try to determine these
values for you using the Autotune option.
4.6.2
Follow these steps to run an Autotune procedure:
1.
Hook up the controller in its desired configuration with the inputs and outputs
connected.
2.
Set the desired Setpoint as detailed in
Section 4.3
3.
Set the desired output to PID mode as detailed in
Section 4.4.
4.
Set the action (
ACtN
) parameter
(PRoG>PID.S>ACtn)
as detailed below.
Setting
Description
RVRS
Reverse: Output increases the process value
dRCt
Direct: Output decreases the process value
5.
Set the Autotune Timeout (
A.to
) parameter (
PRoG>PID.S>A.to).
•
(A.to)
sets the amount of time before the Autotune process gives up and times out in
Minutes and Seconds (
MM.SS
). Note that slowly responding systems should have a
longer time out setting.
6.
Ensure the process value is stable. If the process value is changing, the Autotune will fail.
7.
Select the Autotune (
AUto
) command
(PRoG>PID.S>AUto)
.
•
Confirm Autotune activation. Using return button.
•
The current Process value is displayed flashing.
•
The unit optimizes the P, I, and d settings by turning the output on and measuring
the input response. This may take several minutes depending on the system.
•
When the
Autotune operation completes the unit displays the message “
doNE
”.
8.
If Autotune fails an error code is displayed. Refer to the table below to determine the
cause.
Error Code Description
E007
Displays if the system does not change enough within the Autotune
timeout period.
Check that the output is hooked up and configured correctly or
increase the timeout.
E016
Displays if the signal is not stable before starting an Autotune.
Wait for the system to stabilize before trying to Autotune again.
E017
Displays if the process value is beyond the setpoint.
Adjust the Setpoint or the Action.
