Mitsubishi Electric MELSEC iQ-R Series - Control Data

1136
9 PID OPERATION INSTRUCTION
9.1 Overview
Control data
The details on the control data used by the PID operation instruction are described.
Sampling time: (s3)
Setting range: 1 to 32767 [ms]
Set a cycle (ms) to perform PID operation.
• Auto tuning (limit cycle method)
Set a cycle so that the following condition is satisfied: Operation cycle of the programmable controller < Sampling time
• Auto tuning (step response method)
Set a cycle to 1000ms or longer.
■Maximum error
The maximum error of the sampling time (T
S
) is -(1 operation cycle + 1ms) to +(1 operation cycle).
• When the sampling time (T
S
) value is small
The variation in the maximum error may become a problem. Set the constant scan and execute the instruction, or program it
in the timer interrupt routine.
• When the sampling time value is shorter than one operation cycle of the programmable controller
A PID operation error (11A6H) occurs, but PID operation is executed assuming that the sampling time (T
S
) equals to the
operation cycle. In this case, program the instruction in the timer interrupt routine, clear the value in (s3)+7, and then execute
the instruction.
(1) Reset the value in (s3)+7. (The internal processing register is cleared by the pulse conversion command at the first execution of the interrupt routine.)
(2) Execute the PID operation.
MOVP
K0 D107
PID
D0
D1 D100
D150
X0
• • • (1)
• • • (2)