239
M9002
MOV K2450 D100
MOV K2000 D200
MOV H0001 D201
X0
M0
MOV K0 D215
PLS M0
MOV K1000 D214
MOV H0011 D201
K1000
T200
Y0
T200
M9067
＜
T200 D102
Y1
C0
Y0
Y1
EC1
VS-2TC-EC
Temperature
Expansion
Card
PID D100 D101 D200 D102
MOV H0 EC1D0
MOV K10 EC1D6
MOV EC1D2 D101
M10
M10
= EC1D18 K105
M10
Soldering Pot
VS-PLC
Main Unit
Set point =245°C
Heater
Error indicator
The Example of PID Temperature Control
When design a PID temperature control program, the method below is the recommendable procedure to perform
the PID instruction.
Start using the
control system
Executes the Auto-Tuning
(AT) function to get the
correct PID parameters
Controlled object
changes
The PID instruction is
functioning and gets a
well control
Is it an
expected
result?
No
Yes
Controlled object
doesn’t change
According to the PID
parameters to execute
the PID control
To correct the PID
parameters
The System Structure of Temperature Control
Magnetic contactor
Isolated K-type
Thermocouple
Program Example
When X0=”ON”, it will executes Auto-Tuning function, and then starts the PID control; Otherwise, when X0=“OFF”,
it will executes the PID function directly.
This program is to control the “ON”/“OFF” length percentage in a specific time-span (5 seconds).
When this program starts at the first time, must let X0= “ON”, then by the Auto-Tuning to get parameters of PID.
Otherwise, the PID control will occur error because the related parameters aren’t ready yet.
Let the set point = 245°C, unit= 0.1°C.
Set the Sampling Time of the PID’s Ts = 2 sec.
Set the PID instruction to do the Reverse operation.
When X0 = “OFF” → “ON”, it will start to execute the Auto-Tuning (AT).
D
S3
To set the value of when the AT is ececuting and the output is = 100%
(parameter +14). Since the T200 dominates the control output cycle and its
set value is K1000, thus D214 is set to be K1000.
S3
D
To set the value of when the AT is ececuting and the output is = 0% (parameter
+15).
Set the PID instruction to do the Reverse operation and start to execute the
Auto-Tuning.
Ensure the expansion card in EC1 is the VS-2TC-EC.
Set the external thermocouple to be the K Type.
Set the average of the TC1 to be 10 times.
Read the temperature value of the TC1 and copy it to the D101, unit = 0.1 ℃ .
To operate the PID instruction.
To assign the period of repeating cycle to be 10 seconds.
According to the result of the PID calculation to drive the heater.
The output of PID control loop error alarm.
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