Communication Path Bypass Function - Mitsubishi Electric QJ71E71-100 User Manual

14.7.2

Communication path bypass function

When any of the following redundant system supported applications is used, the path where a communication error
has occurred is automatically bypassed to continue communications if an error occurs in communications with the
E71. The communication path needs not to be changed manually.
• Application that operates on the OPS (except the MELSOFT products such as GX Developer)
• GX Works2
• GX Developer
• PX Developer monitor tool
(1) Operation example of a redundant system supported application at a
communication error
The following provides an example of redundant system supported application operation if an error occurs during
communications with the control system CPU module.
Normal
communications
Control system (station No.1)
Tracking cable
A communication
error occurred.
Control system (station No.1)
(2) Tracking cable
(1) The connected device accesses the control system CPU
module around the path.
(2) Communications with the control system CPU module is
continued via a tracking cable.
Connected device
Standby system (station No.2)
Connected device
Redundant system
supported
application
(1)
Standby system (station No.2)
1.
During normal communications
The station number 1 is operating as a control system,
and the station number 2 as a standby system. The
redundant system supported application is
communicating with the control system CPU module.
2.
Upon a communication error
The station number 1 is operating as a control system,
and the station number 2 as a standby system. (Without
system switching)
[Operation of the redundant system supported
application]
Because a communication error has occurred between
the redundant system supported application and the
E71 mounted with the control system CPU module, the
redundant system supported application automatically
changes the communication path and communicates
with the control system CPU module through the
standby system CPU module.
[Operation of the standby system CPU module]
Because the received data is addressed to the control
system CPU module, data is relayed to the control
system CPU module through the tracking cable.
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