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6.2 Redundant System Network Overview
6.2.2 MELSECNET/H Remote I/O network
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(6) Startup Order of System A and System B
No restrictions apply to the startup order of system A and system B when connected
to the MELSECNET/H remote I/O network.
After starting up system A and system B, the control system and standby system are
determined, and then the data link is started.
(7) Checking the Standby System Operating Status
After power-ON, the status of a MELSECNET/H module on the standby system can
be checked with the following link special relays (SB) on the control system CPU
module side.
• SB0075: Remote master station cyclic transmission status
• SB0076: Remote sub-master station cyclic transmission status
When both of the above link special relays (SB) are OFF, the MELSECNET/H module
on the standby system is running normally.