Product specifications

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Reference Manual
00809-0200-4420, Rev HB
Appendix D: Redundancy
January 2015
Figure D-6. Dual RS-485 Architecture
Note
By default, only the active Gateway in a redundant system will respond to Modbus polling
requests. If simultaneous polling is desired, login to the Gateway web interface, navigate to
Setup>Modbus>Communications and set “Respond when running as redundant standby?” to
Yes. Only use this setting in a dual RS-485 architecture.
Power
Power for the redundant Gateways should be applied after all primary and secondary Ethernet
and RS-485 connections have been made. Using separate uninterruptable power supplies (UPS)
is recommended to ensure availability of the redundant Gateway system.
A. Engineering Station
B. Process Control Network
C. Controller and I/O
D. Dual Serial Card
E. RS-485 Bus
F. Secondary Ethernet
A
B
CD
E
E
F