Mitsubishi Electric MELSEC iQ-R Series User Manual page 379

■System switching request from a network module
The network module on the main base unit of the control system requests the CPU module to switch systems when a
communication error or a disconnection is detected. (The network module on an extension base unit does not request the
CPU module to switch systems when an error is detected.)
When the CPU module of the control system receives a system switching request from the network module, the systems are
switched after the END processing.
Ex.
Operation when the CPU module receives a system switching request from a network module
System switching request from a network module
Program executed
Control system
System A
System B
Standby system
Program stopped
When disconnecting the network cable of the control system for maintenance or other reasons, disconnect the
network cable of the standby system in advance. System switching will not occur even when the network
cable of the control system is disconnected.
The following network modules send a system switching request.
• CC-Link IE Controller Network module
• CC-Link IE Field Network module
• Ethernet interface module with built-in CC-Link IE
• MELSECNET/H network module
• PROFIBUS-DP module
If a network module cable is disconnected, the systems may not be switched depending on the timing of error detection on the
control system and the timing on the standby system. ( Page 387 When the cable for the network module is
disconnected)
END Program stopped
Standby system
System switching
Control system
Program executed
26 REDUNDANT FUNCTION
26.2 System Switching
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