Application Example - IDEC FC4A-C10R2 User Manual

21: PID I
NSTRUCTION

Application Example

This application example demonstrates a PID control for a heater to keep the temperature at 200°C.
In this example, when the program is started, the PID instruction first executes auto tuning according to the designated AT
parameters, such as AT sampling period, AT control period, AT set point, and AT output manipulated variable, and also the
temperature data inputted to the analog input module. The control output remains on to keep the heater on until the tem-
perature reaches the AT set point of 150°C. Auto tuning determines PID parameters such as proportional gain, integral
time, derivative time, and control action.
When the temperature reaches 150°C, PID action starts to control the temperature to 200°C using the derived PID param-
eters. The heater is turned on and off according to the output manipulated variable calculated by the PID action. When the
heater temperature is higher than or equal to 250°C, an alarm light is turned on by the high alarm output.
The analog input module data is also monitored to force off the heater power switch and force on the high alarm light.
Operand Settings
Operand
S1+3 Operation mode
S1+4 Linear conversion
S1+5 Linear conversion maximum value
S1+6 Linear conversion minimum value
S1+10 Integral start coefficient
S1+11 Input filter coefficient
S1+12 Sampling period
S1+13 Control period
S1+14 High alarm value
S1+15 Low alarm value
S1+19 AT sampling period
S1+20 AT control period
S1+21 AT set point
S1+22 AT output manipulated variable
S2+1 Auto/manual mode
Output manipulated variable limit
S2+2
enable
S2+3 Integral start coefficient disable
S2+4 High alarm output
S2+6 Control output
S3 Set point
S4 Process variable
Analog input operating status
Analog input signal type
Analog input data type
D1 Manipulated variable
PID start input
Monitor input
Heater power switch
High alarm light
Note 1: The output manipulated variable during auto tuning is a constant value. In this example, the AT output manipulated
variable is set to the maximum value of 100 (100%), so the control output (S2+6) remains on during auto tuning.
Note 2: When analog I/O module FC4A-L03AP1 is used for the PID instruction, select the binary data to make sure that the
process variable takes a value of 0 through 4095.
21-14
Function
AT (auto tuning) + PID action
Enable linear conversion
1300°C
0°C
100%
70%
500 ms
1 sec
250°C
0°C
1.5 sec
3 sec
150°C
100% (Note 1)
Auto mode
Disable output manipulated variable limits
Enable integral start coefficient (S1+10)
ON: When temperature ≥ 250°C
OFF: When temperature < 250°C
Remains on during auto tuning;
Goes on and off according to the control
period (S1+13) and output manipulated vari-
able (S1+1) during PID action
200°C
Analog input data of analog I/O module 1, ana-
log input channel 0; stores 0 through 4095
Stores 0 through 5
Type K thermometer
12-bit data (0 to 4095) (Note 2)
Stores PID calculation result
Starts to execute the PID instruction
Starts to monitor the analog input module
data for high alarm and operating status
Turned on and off by control output M6
Turned on and off by high alarm output M4
« FC4A M
Description
S U ' M
ICRO MART SER S ANUAL
Allocation No. (Value)
»
D3 (1)
D4 (1)
D5 (13000)
D6 (0)
D10 (0)
D11 (70)
D12 (50)
D13 (10)
D14 (2500)
D15 (0)
D19 (150)
D20 (30)
D21 (1500)
D22 (100)
M1 (OFF)
M2 (OFF)
M3 (OFF)
M4
M6
D100 (2000)
D760
D761
D762 (2)
D763 (0)
D102
I0
I1
Q0
Q1