44
Determining PID Constants (AT, ST, Manual Setup) Section 3-8
Operating Procedure This procedure executes auto-tuning (AT).
3-8-2 ST (Self-tuning)
ST (auto-tuning) is a function that finds PID constants by using step response
tuning (SRT) when Controller operation begins or when the set point is
changed.
Once the PID constants have been calculated, ST is not executed when the
next control operation is started as long as the set point remains unchanged.
ST (self-tuning) is enabled when the “ST” parameter is set to ON in the initial
setting level.
When the ST function is in operation, be sure to turn the power supply of the
load connected to the control output ON simultaneously with or before starting
Controller operation.
When executing self-tuning, turn ON power for the load (e.g., heater) at the
same time as or before supplying power to the Digital Temperature Controller.
If power is turned ON for the Digital Temperature Controller before turning ON
power for the load, self-tuning will not be performed properly and optimum
control will not be achieved.
Note PID Constants
When control characteristics are already known, PID constants can be set
directly to adjust control. PID constants are set in the “proportional band” (P),
“integral time” (I), and “derivative time” (D) parameters in the adjustment level.
Operating Procedure This procedure executes self-tuning (ST).
Adjustment Level
1. Press the O key to move from the operation level to the adjustment level.
2. Press the U key to start execution of AT (auto-tuning).
on will be displayed during AT execution.
3. off will be displayed when AT ends.
Operation Level
4. To return to the operation level, press the O key.
at
off
AT execute/
cancel
at
on
at
off
C
25
0
PV
st
Initial Setting Level
1. Press the O key for at least three seconds to move from the operation
level to the initial setting level.
2. Select the “ST” parameter by pressing the M key.
3. Press the U key to select on. ON is the default.
in-t
5
Input type
st
on
ST
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