Configuring A Network With A Redundant System; Outline Of The Redundant System Operation - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

7 APPLICATION FUNCTIONS

7.10 Configuring a Network with a Redundant System

7.10.1 Outline of the redundant system operation

[Example: When the redundant system is used for a normal station]
Control station
(station No. 3)
A communication
error occurs.
Control system
Control station
(station No. 3)
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This section outlines the operation of a redundant system and describes the network
parameters to be set to configure a redundant system with the MELSECNET/H.
Described below is an outline of the redundant system operation.
(1) Operation of a redundant system
(a) Continuing a data link
If an error has occurred in the control system CPU or a network module,
the system will be switched to the standby system on which system control
and a data link can be continued.
Normal station
(station No. 4)
MELSECNET/H PLC to PLC network
Normal station
(station No. 1)
System switching
request
A communication error occurs in the control system.
Normal station
(station No. 4)
MELSECNET/H PLC to PLC network
Normal station
(station No. 1)
Standby system
Communication
impossible
Normal station
(station No. 2)
Standby system
Normal station
(station No. 2)
Control system
MELSEC-Q
The normal station of
the new control system
continues a data link.
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