Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 1156

■Sampling period
Sampling period is a cycle in which PID operation is performed. The measurement time of a single scan is added to the total
measurement time up to the last scan every time the PIDCONT instruction is executed. The total measurement time reaches
or exceeds the set sampling period, PID operation of the corresponding loop is performed.
Set the sampling period used in PID operation in increments of 10ms.
Ex.
When the sampling period is 50ms
Powering on the CPU module
PIDCONT
0
Program
PIDINIT
0ms
PV
PV<SV
PID operation is performed
with the initial value.
PV: Measured value
SV: Set value
Since the sampling period is measured at execution of the PIDCONT instruction, a value smaller than the
program scan time cannot be set as the sampling period. If set, PID operation is performed with a scan time.
10 PID CONTROL INSTRUCTIONS
1154
10.1 Overview
PIDCONT PIDCONT
END 0 END 0
19ms 19ms
19ms 19+19=38ms
PV<SV PV<SV
PIDCONT PIDCONT
0 0
END END
19ms 19ms
38+19=57ms 7+19=26ms
PV>SV PV<SV
PID operation is performed
with a sampling cycle of 50ms.
The measured value is
changed to 57-50=7ms.
PIDCONT PIDCONT
0 0
END END
19ms 19ms
26+19=45ms 45+19=64ms
PV<SV PV>SV
PID operation is performed
with a sampling cycle of 60ms.
The measured value is
changed to 64-60=4ms.
PIDCONT
0 END
END
19ms
4+19=23ms
PV<SV