33
3
Conditions under which the self-tuning runs:
q
At power-on:
The self-tuning runs when all of the following conditions are met.
• The SV that appears at power-on is not the same one when the , , , and
were set previously. (i.e. the
, , , and
set by the self-tuning, auto-tuning, manual setting, and writing by communications tools at
previous time)
• The (SV-PV) at power-on is larger than (the value of
×
input range) or (the set value of
).
w
When the SV is changed:
The self-tuning runs when all the conditions below are met.
• The changed SV is larger than the SV that was set when the , , , and
were selected previously.
• The changed amount of the SV is larger than 0.
• The changed amount of the SV is larger than (the set value of
×
input range) or (the set value of
).
e
When output becomes unstable:
The self-tuning runs when control becomes unstable and the hunting of the operating output (MV) occurs. (The self-
tuning runs only once as long as the SV is not changed.)
r
When the control standby mode is cancelled:
The self-tuning runs by the same reason as “
q
At power-on” are met.
* Only when the PXR is set to standby mode at power-on.
4
Conditions under which the self-tuning does not run:
q
During control standby mode
w
During two-position control (Parameter of = 0)
e
During auto-tuning operation
r
During ramp-soak operation
t
Error display (
or
is displayed.)
y
During dual output (The set value of the parameter of
is larger than 4.)
u
When setting the parameters of , , , and
manually (including the setting written by communications
tools)
5
Conditions under which the self-tuning is suspended:
q
At the condition described in
4
shown above
w
When the SV is changed during self-tuning operation
e
When the self-tuning operation can not be completed within approx. 9 hours
6
Caution
q
Once the PID constant is set, the self-tuning does not operate at next power-on as long as the SV is not
changed.
w
For an accurate tuning, be sure to power on the device to be controlled before or at the same time as the
PXR is powered on. If the PXR has to be powered on first for reasons of the system configuration, perform
the auto-tuning with the PID or FUZZY control.
e
If the device to be controlled is powered on under temperature change (especially when it rises), accurate
tunings can not be performed. Be sure to power on the PYX when the temperature of device to be controlled
is stabilized.
r
The self-tuning does not run for cooling system control under Direct Action output (Parameter
= 2 or 3).
t
In case the control is not stable after performing the self-tuning, change the algorithm to the PID or FUZZY
control and perform the auto-tuning.
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