13. Automatic Tuning
The Auto Tune feature automatically sets the tuning parameters for Menu 3 parameters ‘Pb’
Proportional Band, ‘ti’ Integral time (reset), and ‘td’ Derivative time (rate). This also applies to
the secondary (optional cooling) output parameters (CPb, Cti, and Ctd).
The controller must be wired to the process before proceeding.
1. Use the arrow keys to adjust the setpoint (SV) to the desired level.
2. Ensure that Proportional Band (‘Pb’ or ‘CPb’) in Menu 3 is not set to zero (zero is
reserved for ON/OFF control; Auto Tune does not apply in ON/OFF control mode).
3. Set the ‘at’ parameter, in Menu 3, to YES 1, for normal tuning, or YES 2, to a place a
buffer at the setpoint (10% of full scale). ‘YES 2’ is less aggressive form of tuning for
delicate processes.
4. The rightmost decimal on the PV display begins flashing when Auto Tune begins.
5. Auto Tune will run two cycle oscillations. After that, the controller will use the
learned PID settings. The PID values are stored in nonvolatile memory.
6. An Auto Tune session may require only several minutes for quick processes but may
require up to two hours for slower processes. An error will appear after 2 hours. This
could mean that the control system is not in a closed loop with the controller, re-
check the wiring and system configuration. Contact Extech if issues persist.
7. When Auto Tune is complete, the decimal will stop flashing.
8. To abort an Auto Tune session, set the ‘at’ parameter in Menu 3 to no.
14. Automatic and Manual Control Modes
Automatic Control
Automatic Control is the normal mode of operation. In Auto mode the controller automatically
adjusts the control output to bring process to setpoint as described.
Manual Control
Manual control allows you to manually adjust the control outputs from 0.0 to 100.0%.
1. Set the ‘HAND’ parameter, in Menu 1, to YES to access Manual control. The SET key takes
you through Menu 1.
2. The rightmost decimal in the SV display will flash while the controller is in the Manual
mode.
3. Go to the ‘OUTL’ parameter in Menu 1 to view the output percent.
4. Use the up/down arrow keys to change the output percentage (0 ~ 100%).
5. The controller will alternately display the PV and the control output level.
6. To return to normal operation, set the ‘HAND’ parameter to NO.
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