Inovance MD380 Series, User Manual

Page: 209 / 304

MD380 User Manual Desc
ription of Function Codes
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Group FA: Process Control PID Function
PID control is a general process control method. By performing proportional, integral and
differential operations on the difference between the feedback signal and the target signal,
it adjusts the output frequency and constitutes a feedback system to stabilize the controlled
counter around the target value.
It is applied to process control such as flow control, pressure control and temperature
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Figure 6-28 Principle block diagram of PID control
1
Ti
1
S
+
+
Target
-
Td x S +1
1
P
Feedback
PID output
Function Code Parameter Name Setting Range Default
FA-00 PID reference source
0: FA-01
1: AI1
2: AI2
3: AI3
4: Pulse reference (DI5)
5: Communication reference
6: Multi-reference
0
FA-01 PID digital setting 0.0%–100.0% 50.0%
FA-00 is used to select the channel of target process PID reference. The PID reference is a
relative value and ranges from 0.0% to 100.0%. The PID feedback is also a relative value.
The purpose of PID control is to make the PID reference and PID feedback equal.
Function Code Parameter Name Setting Range Default
FA-02 PID feedback source
0: AI1
1: AI2
2: AI3
3: AI1 – AI2
4: Pulse reference (DI5)
5: Communication
reference
6: AI1 + AI2
7: MAX (|AI1|, |AI2|)
8: MIN (|AI1|, |AI2|)
0
This parameter is used to select the feedback signal channel of process PID.
The PID feedback is a relative value and ranges from 0.0% to 100.0%.
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