Azbil C1M - Page 88

5-30
Chapter 5. Functions
Handling Precautions
• Before starting AT, check that the PV input and the actuators (heater power,
etc.) are ready for control.
• If CtrL (control method) is set to 0 (ON/OFF control), AT cannot start. Change
the control method setting to 1 (PID control).
• Conditions for starting AT:
•
The device is in RUN and AUTO modes.
•
No PV input error has occurred.
•
The setting for “MV switching point PV in AT” is within the PV input range.
AT (automatic tuning) (p.5-24) (for “Type of MV switching point at AT”)
PV input range type (p.5-2) (for the PV input range)
• If any of the following is detected during AT, AT will stop without changing the
PID constants:
•
Switch to READY mode
•
Switch to MANUAL mode
•
PV error
•
Change in the setting of “control method,” “heat/cool control,” “control
operation” (only when “heat/cool control” is set to 0 (not used)), “sampling
cycle,” and “control algorithm”
•
Change in the setting of “MV low limit” (OL-1 to 8), “MV low limit at AT” (At.OL),
“MV high limit” (OH-1 to 8), or “MV high limit at AT” (At.OH) that would prevent
change in the two-value output during AT
• For forcible termination of AT by At (AT stop/start selection) in the mode bank
or by the internal contacts to which the function to stop/start AT is assigned,
see the section below:
5 - 7 Digital Input (DI) / Internal Contacts (p.5-47)
If AT is forced to stop, At.Er (auto tuning error) is set to Er.On (abnormal). At.Er
(auto tuning error) can be reset to Er.OF (normal)) by any of the following
operations.
•
Change the setting of At.Er (auto tuning error) to Er.OF (normal).
•
Try executing AT again until it ends normally.
•
Turn the power off and then back on.
• If C26 (heat/cool control) is set to 2 (use (shared PID)), specify AT MV low limit
(at.ol) / AT MV high limit (at.oh) and MV low limit (ol-1 to 8) / MV high limit
(oh-1 to 8) so that both values that are output to the MV are 50 % or more.
• If C26 (heat/cool control) is set to 1 (use (individual PID)),
•
The MV is limited by “MV low limit at AT” (At.OL) / “MV high limit at AT” (At.OH).
•
The heating MV is limited by “MV low limit” (OL-1 to 8) / “MV high limit” (OH-1
to 8) for the PID constants.
•
The cooling MV is limited by “cool-side MV low limit” (OL.1C to 8C) / “cool-side
MV high limit” (OH.1C to 8C).