Chapter 6 Usage of Various Functions
6-21
b) Auto-tuning Control function
(parameter setting by built-in function of PLC option card)
■
Setting Value (when Resistor Thermal Detector sensor is used)
960(60
o
C),1120(70
o
C),1280(80
o
C),1600(100
o
C)
■
Operation Scan Time: Set by 1 second (Setting value = 10)
■
Present Value setting: D4980
(Temporary D area to save the current temperature measured by temperature
sensor)
■
Tuning method: Relay response method
c) Remote I/O (A/D Converter)
■
Input range: DC 4~20 mA
■
Data saving area of converted value of A/D: D4980
d) Remote I/O (D/A Converter)
■
Output range: DC 4~20 mA
■
Data saving area of converted value of D/A: D4982
(3) Program Explanation
a) PID operation explanation (without Auto-tuning function)
•
Measure current temperature (-200~600
°
C) by RTD module then digital conversion
value(0 ~ 4000) is stored to D4980
•
PID8 instruction will calculate manipulate value (MV : 0 ~ 4000) based on PID
parameter settings (P_GAIN, I_TIME, D_TIME, etc.) and PV from RTD module.
Then, the calculated MV is output to the channel 0 of D/A module. (PID operation
Done bit: bit0)
•
D/A module will convert the MV to analog signal and output to the actuator (power
converter).
b)PID operation explanation (with A/T function)
•
Measure current temperature (-200~600
°
C) by RTD module then digital
conversion value(0 ~ 4000) is stored to D4980
•
PID8AT instruction will calculate manipulate value (MV : 0 ~ 4000) based on the
SV and PV from RTD module. Simultaneously, the PID8AT instruction will
calculate P,I and D parameters.
•
The END bit of auto tuning status device will be 1 when the auto tuning is
completed. Then, PLC option card will start PID operation with PID parameters
that are calculated by Auto-tuning function.
