Omron E5AZ User Manual

37
Determining PID Constants (AT, ST, Manual Setup) Section 3-8
3-8-2 ST (Self-tuning)
ST (self-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 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 E5AZ/E5EZ.
Execute self-tuning (ST).
1,2,3... 1. Press the 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 key.
3. Press the key to select “on” (default).
4. To return to the “operation level,” press the key. The temperature dis-
play blinks during self-tuning (ST) execution.
3-8-3 ST Start Conditions
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.
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.
st
Operation Procedure
Input typ
e
Initial setting level
ST
ST
5
At Start of Program Execution When Set Point Is Changed
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
execution is smaller than the set point dur-
ing reverse operation, and is larger than
the set point during direct operation.
4. No reset from input error
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 (cur-
rent 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.) (See note 3.)

Omron E5AZ Specifications

General

Brand	Omron
Model	E5AZ
Category	Temperature Controller
Language	English