The 4400 has two (2) types of Automatic Tuning on the 4400 series control: Self Tune & Pre-Tune.
Self Tune:
Self Tune monitors the input for any oscillations around the setpoint during a dwell and attempts to tune until the Input is stable. When active the AT light on the front of the control will be lit constanly. Self Tune will stay active until it is shut off. While Self Tune is a very useful and powerful tool, certain applications can pose a problem. Self Tune will try to tune out any oscillation even if it is not possible. An example would be with some types of presses where cold material is loaded periodically. The process naturally cools down when the press is loaded. This oscilation is not possible to tune out completely. Self Tune can in some cases tune to the point where the control becomes very sluggish and require manually setting the control parameters for reasonable control again.
Pre Tune:
Pre Tune is a one-shot tuning sequence that is used when the control is not running a profile. When active the AT light on the front of the control will be flashing. The input must be at least 5% of the controller range away from the setpoint to activate. When Pre Tune is activated the control will turn the main output to 100% ON allowing the input to go toward the setpoint at its highest speed. Some time before reaching the setpoint the control will shut off the main output and turn on its secondary output (if installed) and wait untill the signal changes direction. From the data it obtains during the PreTune cycle it calculates and loads the tuning parmeters into the control. When it is finished with the cycle PreTune deactivates and controls (using the new parameters at the setpoint.
To Activate/Deactivate Self Tune or PreTune:
With the control in base mode (Run and Hold indicating lights are OFF) press the Scroll key until the Message Display shows SelfTune or Pre Tune as desired then Press Mode & the Up Arrow keys together to turn it ON and Mode and Down Arrow keys to shut it OFF.