Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 314

7 APPLICATION FUNCTIONS
MELSEC-Q
(d) Program example 2 (when a redundant system is the target system)
When the target station is in a redundant system, the ZNRD instruction
must be executed after judging whether it is a control system.
The program example shown below is an interlock program for reading D10
to D14 of the control system CPU of the redundant system consisting of
station Nos. 1 and 2 into D200 to D204 of the host station.
Provide the identical interlock for the ZNWR instruction.
7 - 90 7 - 90