5
5.3 The System Switching Function
5.3.1 System Switching Method
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(b) System switching requested by the network module
• When the control system CC-Link IE Controller Network module,
MELSECNET/H module, or the Ethernet module detects a communication
error or wire break
*1
, the module requests system switching to the CPU
module. (The standby system CC-Link IE Controller Network module,
MELSECNET/H module, or the Ethernet module does not request system
switching, even if the module detects a communication error or wire break
*1
.)
• When the PROFIBUS-DP master module detects a module fault or
communication failure with DP-Slaves, the module requests system switching
to the CPU module. (The standby system PROFIBUS-DP master module
does not request system switching, even if the module detects a module fault
or communication failure with DP-Slaves.)
When receiving the system switching request from the network module, the
control system CPU module will perform a system switching at END processing.
Diagram 5.24 shows the processes that take place when the system switching
request is received from the network module.
*
1: For the Ethernet interface modules, only the QJ71E71-100 can detect wire break.
Diagram 5.24 System switching operations requested by the network module
Tracking cable
Tracking cable
Control start
System switching request
System switching
Ethernet
Communication
error or
disconnection
Ethernet
Communication
error or
disconnection
System A
END
Control
system
System B
Standby
system
Control
system
RUN
(Execute program)
Normal Standby
RUN (Stop
Normal Standby
RUN
(Stop program)
RUN
(Execute program)
Standby
system
System
switching
System switching
requested by the
Ethernet interface
module
System A -
Control System
System B -
Standby System
System A -
(Control System
Standby System)
System B -
(Standby System
Control System)