Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 360

7 APPLICATION FUNCTIONS
<Redundant system using redundant CPUs>
<Redundant system using Q4ARCPUs>
Parameters
Sequence programs, etc.
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(2) Redundant system project
In a redundant system using redundant CPUs, one project is required to create
parameters and sequence programs and there is no need to create 2 projects for
each of the control and standby systems.
The network modules mounted to the control and standby systems can
communicate with each other with a single network parameter.
System A
(control system)
Parameters
Sequence programs,
etc.
System A
(control system)
Q4AR
Network
CPU
module
Project for system A
(3) Station type at startup of the redundant system (when the
redundant system is a control station)
At the time of startup of the redundant system, the network module installed with
the control system CPU is identified as a "control station," and the network
module installed with the standby system CPU is identified as a "normal station".
System B
(standby system)
Project
In a redundant system using redundant CPUs,
a project is created and written to both systems.
System B
(standby system)
Q4AR
Network
CPU
module
Project for system B
Parameters
Sequence programs, etc.
MELSEC-Q
In a redundant system using Q4ARCPUs,
2 projects must be created for each of systems
A and B and written to them.
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