Simple Dual-Structured Network (High Performance Model Qcpu And Process Cpu) - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

7 APPLICATION FUNCTIONS

7.7 Simple Dual-Structured Network (High Performance model QCPU and Process CPU)

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By installing two network modules, a regular network module and a standby network
module, to each CPU module, data linking can be continued by switching to link data
refreshing with the standby network when a faulty area is detected on the regular
network due to wire breakage, etc. When there is no error, both the regular and
standby network modules will be executing data linking at the same time.
POINT
The Basic model QCPU, Redundant CPU, Universal model QCPU, and safety
CPU do not have the special relay for the simple dual-structured network.
Therefore, the simple dual-structured network system cannot be configured as
below.
(1) The switching between the regular and standby networks (i.e., which network the
CPU module refreshes) is performed by the sequence program.
By checking the data link status (SB0074, SW0074 to 0077) of each station, the
sequence program refreshes with the standby network modules when an error is
detected in the regular network.
MELSEC-Q
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