Mitsubishi Electric MELSEC FX3U Programming Manual page 498

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
2. Set items
Set item
Target value
S
1
(SV)
Measured
S
2
value (PV)
Parameter
S
3
Output value
D
(MV)
*1.
3. List of parameters
Sampling time (Ts)
S
3
Operation
S +1
3
setting (ACT)
Input filter constant (α)
+2
S
3
Proportional gain (KP)
S +3
3
Integral time (TI)
S +4
3
Derivative gain (KD)
+5
S
3
Derivative time (TD)
S +6
3
496
• Set the target value (SV).
• PID instruction does not change the contents of setting.
• Caution on using the auto tuning (limit cycle method)
If the target value for auto tuning is different from the target value for PID control,
it is necessary to set a value including the bias value first, and then store the
actual target value when the auto tuning flag turns OFF.
This is the input value in PID control loop.
1) Auto tuning: In the case of limit cycle method
Twenty-nine devices are occupied from the head device specified in
2) Auto tuning: In the case of step response method
a) Operation setting (ACT): When bits 1, 2 and 5 are not all "0"
*1
Twenty-five devices are occupied from the head device specified in
b) Operation setting (ACT): When bits 1, 2 and 5 are all "0"
Twenty devices are occupied from the head device specified in
1) In case of PID control (normal processing)
Before driving PID instruction, the user should set the initial output value.
After that, the operation result is stored.
2) Auto tuning: In the case of limit cycle method
During auto tuning, the ULV or LLV value is output automatically.
When auto tuning is finished, the specified MV value is set.
3) Auto tuning: In the case of step response method
Before driving PID instruction, the user should set the initial output value.
During auto tuning, PID instruction does not change the MV output.
When auto tuning is not used, the number of points is the same as the number in the step
response method are occupied.
to +28
S S
3 3
Set item
1 to 32767 (ms)
0: Forward operation,
bit0
1: Backward operation
0: Input variation alarm is invalid.
bit1
1: Input variation alarm is valid.
0: Output variation alarm is invalid.
bit2
1: Output variation alarm is valid.
bit3 Not available
0: Auto tuning is not executed.
bit4
1: Auto tuning is executed.
0: Upper and lower limits of output
bit5
1: Upper and lower limits of output
0: Step response method
bit6
1: Limit cycle method
bit7 to bit15 Not available
0 to 99 (%)
1 to 32767 (%)
0 to 32767 (× 100 ms)
0 to 100 (%)
0 to 32767 (× 10 ms)
Description
Setting Value
value are not valid.
value are valid.
16 External FX Device – FNC 80 to FNC 89
16.9 FNC 88 – PID / PID Control Loop
S .
3
S
3
S .
3
Remarks
It cannot be shorter than the operation
cycle.
Operation direction
Do not set to ON bit 2 and bit 5 at the same
time.
Do not set to ON bit 2 and bit 5 at the same
time.
Select the auto tuning mode.
When "0" is set, the input filter is not
provided.
When "0" is set, it is handled as "\" (no
integration).
When "0" is set, the derivative gain is not
provided.
When "0" is set, the derivative operation is
not executed.
Number of
occupied
points
1
1
29
.
25
20
1