Omron E5C series, User Manual

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4 - 27
4 Basic Operation
E5@C Digital Temperature Controllers User’s Manual (H174)
4-
9 Det
e
rm
inin
g PID
Con
s
tan
ts (
A
T
, S
T
, Manual Set
up)
4
4-9-3 R
T
(R
ob
ust T
u
n
ing) (Used f
o
r A
T
or ST
.)
*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 within the ST stable range or less.
In the following instances, PID constants are not changed by self-tuning (ST) for the present set
point.
(1) When the PID constants have been changed manually with ST set to ON.
(2) When auto-tuning (AT) has been executed.
To execute self-tuning again after completing the above operations, set the ST parameter to OFF
and then set it to ON again.
z
ST Stable Range
The ST stable range determines the condition under which ST (self-tun-
ing) functions.
This procedure sets the ST stable range to 20.0
°
C.
Operating Procedure
1
Press the
M
Key several times in the Advanced Function
Setting Level to display the
st-b
(ST Stable Range) parameter.
Advanced Function Setting
Level
2
Press the
U
or
D
Key to set the value to 20.0.
The default is 15.0.
4-9-3 RT (Robust Tuning) (Used for AT or ST.)
• When AT or ST is executed with RT selected, PID constants are automatically
set that make it hard for control performance to deteriorate even when the
characteristics of the controlled object are changed.
• RT can be set in the Advanced Function Setting Level when PID control has
been set.
• The RT mode cannot be selected while an analog input is set.
• Selecting the RT mode in the following cases will help to prevent hunting from
occurring.
• When the set temperature is not constant and is changed in a wide range
• When there are large variations in ambient temperatures due to factors such
as seasonal changes or differences between day and night temperatures
• When there are large variations in ambient wind conditions and air flow
• When heater characteristics change depending on the temperature
• When an actuator with disproportional I/O, such as a phase-control-type
power regulator, is used
• When a rapidly heating heater is used
• When the control object or sensor has much loss time
• When hunting occurs in normal mode for any reason
* PID constants are initialized to the factory settings by switching to RT
mode.
* When the RT mode is selected, the Integral/Derivative Time Unit pa-
rameter changes to 0.1 s.
15.0
st-b
ST Stable
Range
20.0
st-b
000
rt