Chapter 7. Usage of Various Functions
7-33
Processⓑ reaction curve method(PRC method).
• PID parameters are obtained by step response of process.
• It is useful fo r time 1
st
order time delay system expressed as following
1+
−
Ts
e
K
Ls
• Obtained parameters may not accurate if the process can’t approximated to 1
st
order system, In this
case, use relay response method.
ⓒ PWM Tuning
PWM (Pulse Width Modulation) is a output method which changes on-off duty of output pulses by
calculated manipulation value. The figure below shows an example of PWM output. Using PWM output,
PID control system can be constructed easily without D/A conversion module and power regulator. The
output can be designated when PWM is selected, but only main unit’s contacts can be used for PWM
output. (The expansion module’s cannot be used.)
5) Program example
(1) System configuration
80% of SV
MV
4000
63% of SV
Time constant(T)
GMWIN
V4.1 above
RS-232C
TPR
Heater
Electric Oven
(PV: temperature)
(MV: 4~20mA)
GM7U
G7F-DA2I
G7F-
RD2A
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