Autotuning; Primary Menu - Fuji Electric PXZ Series Operation Manual

AUTOTUNING

Before initiating the autotune function, first decide if you would like
to autotune at setpoint or 10% of full scale below setpoint. Set the
setpoint (SV), alarms (AL, AH) and the cycle time (TC). Bring your
process near setpoint before starting the autotune procedure.
Set the parameter AT to either "1"(to autotune at setpoint) or "2" (to
autotune at 10% of full scale below setpoint) and press ENT key to
start auto-tuning. The point indicator at lower right will then start
blinking. When the auto-tuning is completed, the point indicator stops
blinking and the parameter AT will automatically be set to "0."
Duration of the autotune process varies with every application. The
auto-tuning process may take between 1 and 30 minutes to complete.
If it fails to complete, an abnormality may be suspected. In this case,
recheck the wiring, control action, and input type code. Refer to page
16 and Appendix A for additional details.
The PID parameters calculated by autotuning will be retained even if
the power is lost. However, if the power is turned off during the auto-
tuning process, you must restart autotuning. To abort the autotune
procedure, set AT to "0." Auto-tuning has to be repeated if there is a
significant change in SV, P-SL or P-SU, or in the controlled process.
Autotuning can also be performed while fuzzy control is selected.
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PRIMARY MENU SETTINGS
PARAMETER DESCRIPTION
-
SV Main Setpoint Variable: The main setpoint variable is
the control point you wish to maintain. The main set-
point variable is set within the input range, between
the (P-SL) and the (P-SU) settings.
ProG Ramp/Soak Command: The Ramp/Soak program auto-
matically changes the setpoint value with time in
accordance with a preset pattern. ProG switches the
operation modes.
Setting: oFF : Normal operation is performed
rUn : Ramp/Soak operation is performed
hLd : Ramp/Soak operation is suspended
P Proportional Band: The proportional band is that area
around main setpoint where the control output is nei-
ther fully on nor fully off.
Setting range: 0.0 to 999.9% of full scale
For On/Off control, set to "0"
I Integral Time (reset): The Integral Time is the speed at
which a corrective increase or decrease in output is
made to compensate for offset which usually accom-
panies proportional only processes. The more Integral
Time entered, the slower the action. The less Integral
Time entered, the faster the action. Enter as little
Integral Time as necessary to eliminate offset without
overcompensating resulting in process oscillation.
Setting Range: 0 to 3200 secs
Integral Action is turned off when set to "0"
d Derivative Time (Rate): The Derivative Time is that time
used in calculating rate of change and thermal lag in
helping eliminate overshoot which results in response
to process upsets. This overshoot usually accompanies
proportional only and proportional-integral processes.
The derivative action dampens proportional and inte-
gral action as it anticipates where the process should
be. The more Derivative Time entered, the more damp-
ing action. The less Derivative Time entered, the less
damping action. Enter as much Derivative Time as nec-
essary to eliminate overshoot without over-damping
the process resulting in process oscillation.
Setting Range: 0 to 999.9 secs
Derivative Action is disabled when set to "0"
TEMP
Proportional
Action
9
Setpoint
Integral
Action
Derivative
Action
TIME