Mitsubishi Electric MELSEC-Q Series User Manual page 200

(2) Functions
(a) Operation chart of the G(P).RIFR instruction
Master station
CPU module
Command
G(P).RIFR
Device
1.
The automatic update buffer specified by n1 and n2 of the master station specified by Un is
accessed.
2.
The data read after the device specified by (D) is stored.
(b) Timing of reading data
The G(P).RIFR instruction reads data while it is being executed.
But the concurrent execution of the instruction from two or more locations is not allowed for the same intelligent
device station.
(c) The number of allowable read points
The maximum number of points that can be read by the G(P).RIFR instruction is 4096.
(d) Basic number of steps
The basic number of steps of the G(P).RIFR instruction is nine.
(e) Assignment of the automatic update buffer
The assignment of the automatic update buffer is performed in "Station Information Setting" of the network
parameter of a programming tool. (
198
Master station
1.
Automatic
update buffer
2.
Target station
Buffer memory
Communication
starts when
conditions are
met.
Page 102, Section 7.3.2 (2))
Intelligent device station
Automatic update
buffer memory