Mitsubishi Electric MELSEC FX3U Programming Manual page 500

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Cautions
1. When using two or more PID instructions
Two or more PID instructions can be executed at the same time. (There is no limitation in the number of
loops.) However, make sure that
to each other.
2. Number of devices occupied for parameters starting from
1) In the limit cycle method
- Twenty-nine devices are occupied from the head device specified in
2) In the step response method
- Operation setting (ACT): When bits 1, 2 and 5 are not all "0"
Twenty-five devices are occupied from the head device specified in
- Operation setting (ACT): When bits 1, 2 and 5 are all "0"
Twenty devices are occupied from the head device specified in
3. When specifying a device in the latched area backed up against power failure
For the output value (MV) in the PID instruction, specify a data register (D) outside the latched area.
Program example
When specifying a data register in the latched area, make sure to clear the latched (backed up) contents
when the PLC mode is set to RUN using the following program.
Program example
M8002
Initial pulse
Error
When an operation error occurs, the special auxiliary relay M8067 turns ON, and the error code is stored in
the special data register D8067.
498
,
S
3
RST D***
Data register number in the latched area specified in
and other operands specified in each instruction are different
D
D
→ For the error code, refer to Section 38.4.
16 External FX Device – FNC 80 to FNC 89
16.9 FNC 88 – PID / PID Control Loop
S
3
.
S
3
.
S
3
.
S
3