PARAMETERS
139
(5) Parameter setting
Parameter
Number
Setting
Name
Description
0
No PID action
20
For heating, pressure control,
etc.
PID reverse action
128
21
PID
action
selection
For cooling, etc.
PID forward action
0.1 to
1000%
If the proportional band is narrow (parameter setting
is small), the manipulated variable varies greatly
with a slight change of the process value. Hence, as
the proportional band narrows, the response
sensitivity
(gain) improves but the stability
deteriorates, e.g. hunting occurs.
Gain K = 1/proportional band
129
9999
PID
propor-
tional
band
No proportional control
0.1 to
3600 s
Time required for the integral (I) action to provide
the same manipulated variable as that for the
proportional (P) action. As the integral time
decreases, the set point is reached earlier but
hunting occurs more easily.
130
9999
PID
integral
time
No integral control.
0 to 100%
Set the upper limit. If the feedback value exceeds
the setting, the FUP signal is output. (Process value
of 4mA is equivalent to 0% and 20mA to 100%.)
131
9999
Upper
limit
No function
0 to 100%
Set the lower limit. If the feedback value falls below
the setting, the FDN signal is output. (Process value
of 4mA is equivalent to 0% and 20mA to 100%.)
132
9999
Lower
limit
No function
133
0 to 100%
PID
action set
point for
PU
operation
Only valid for the PU command in the PU operation
or PU/external combined operation mode.
For external operation, the voltage across 2-5 is the
set point.
(Pr. 902 value is equivalent to 0% and Pr. 903 value
to 100%.)
0.01 to
10.00 s
Time required for the differential (D) action to provide
the same process value as that for the proportional
(P) action. As the differential time increases, greater
response is made to the deviation change.
134
9999
PID
differential
time
No differential control.
(6) Adjustment procedure
Adjust the PID control parameters, Pr. 128 to Pr. 134.
Parameter setting
Set the output terminal functions, Pr. 190 to Pr. 192.
Terminal setting
Run
4
