4-29
Chapter 4. Functions
z
z
AT abnormal end
If AT does not start after the AT start operation, or if AT stops without changing the
PID constants even though there was no AT stop operation, an AT abnormal end is
generated and the data of the corresponding loop among the standard bit codes for
"AT abnormal end" for loops 1 to 4 changes to 1.
z
z
Clearing an AT abnormal end
To clear an AT abnormal end, do one of the following.
•
Make sure that AT is executable and then start it.
•
Press the AUTO TUNING
[FAIL]
button on the mode menu screen, and press the
[CLEAR]
button on the confirmation screen (see the figures below).
•
Power the device off and back on.
［
FAIL
］
button
［
CLEAR
］
button
Handling Precautions
•
Before starting AT, make the PV (analog input) and the actuators (heater
power, etc.) ready for control.
•
If the control action is set to ON/OFF, AT cannot be started. Set the control
action to PID.
•
For AT to start, there must be no PV (analog input) errors, and RUN mode,
AUTO mode, and fixed value output is not selected.
•
While AT is running, if the mode is switched to READY or MANUAL, if fixed
value output is selected, or if a PV (analog input) error or a power failure
occurs, AT stops without changing the PID constants.
•
If heating/cooling control is not used, the MV low/high limit during AT and the
PID constant MV low/high output will be assigned to the MV. Set so that the
largest possible common area for these two ranges is left.
