Watlow CLS - Manual (Page 68)

60 CLS User’s Guide
Using the CLS
Autotune
If you set the current loop's control status to TUNE and press Enter, the
controller automatically sets the loop to Manual control, 100% output.
(If you selected a continuous output limit, the controller sets the loop to
the output limit.) The autotune function then calculates the appropriate
PID constants for the loop and puts the loop in automatic control with
the calculated PID values.
The Autotune function will abort if:
• Process variable goes over 75% of the setpoint. Remember, the con-
troller is at 100% output or at the output limit you set.
• It has not calculated PID constants after 10 minutes (due to heater
failure, sensor failure, et cetera.)
If the autotune function aborts, it puts the loop into its previous control
state (Automatic control or Manual control at the previous output
percentages.)
To automatically tune a loop, follow these steps:
1. Make sure the process is cold (or stable and well below setpoint).
2. Initiate Autotune:
a. Use the front panel keypad to go to Single Loop Display
b. Press the Man/Auto key
c. Choose Tune
d. Press Enter.
The Tune indicator will begin flashing and the controller will go back to
Single Loop Display. The Tune indicator will keep flashing as long as
the loop is tuning.
Ramp/Soak
If you have a CLS without the Ramp/Soak option, pressing the Ramp/
Soak key has no effect. If you have a CLS with Ramp/Soak installed,
please refer to the Ramp/Soak Appendix at the end of this manual.