St (Self-Tuning); St Start Conditions - Omron E5CN User Manual

Determining PID Constants (AT, ST, manual setup)
3-8-2

ST (self-tuning)

st
Operation Procedure
1,2,3...
Initial setting level
Input type
ST
ST
3-8-3

ST start conditions

1,2,3...
30
The ST (self-tuning) function executes tuning from the start of program execu-
tion to calculate PID constants matched to the control target.
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 executed when the "ST" parameter is set to "ON" in the "ini-
tial 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
operation of the E5CN.
Execute self-tuning (ST).
1. Press the
level" to the "initial setting level".
2. Select the "ST" parameter by pressing the
3. Press the
4. To return to the "operation level," press the
play blinks during self-tuning (ST) execution.
Self-tuning by step response tuning (SRT) is started when the following condi-
tions are met after program execution is started and the set point is changed.
At Start of Program Execution
1. The set point at the start of program execu-
tion differs from the set point (See Note 1)
when the previous SRT was executed.
2. The difference between the temperature at
start of program execution is larger than
(current proportional band × 1.27+4 ° C) or the
(ST stable range) whichever is larger.
3. The temperature at the start of program ex-
ecution is smaller than the set point
during reverse operation, and is larger than
the set point during direct operation.
4. No reset from input error
Note (1) The previous SRT-implemented set point is called the set point obtained
by calculating the PID constant by the previous SRT.
(2) In this state, the measurement point is within the ST stable range.
(3) In this state, the change width of the PV every 60 seconds is at the ST
stable range or less.
PID constants are not modified for the currently preset set point by self-tuning
(ST) in the following instances:
1. When the PID constants have been changed manually with ST set to ON.
2. When auto-tuning (AT) has been executed.
key for at least three seconds to move from the "operation
key to select "on" (default).
1. The new set point differs from the set point
(See Note 1) used when the previous SRT
was executed.
2. The set point change width is larger than
(current proportional band × 1.27+4 ° C) or the
(ST stable range) whichever is larger.
3. During reverse operation, the new set point
is larger than the set point before the
change; and during direct operation, the
new set point is smaller than the set point
before the change.
4. The temperature is in a stable state (See
Note 2). (An equilibrium state is acceptable
when the output is 0% when the power is
turned ON.)
Section 3-8
key.
key. The temperature dis-
When Set Point Is Changed