Emerson 1420 Reference Manual page 45

Reference Manual
00809-0200-4420, Rev HC
RS-485 (serial)
An RS-485 connection supports Modbus RTU protocol. Using this connection type, the Gateway
is wired to an RS-485 bus which typically leads to a serial I/O card or Modbus I/O card (see
Figure
Figure 5-3. RS-485 LAN Architecture
A. Engineering Station
B. Primary Control Network
C. Secondary Control Network
D.Controller and I/O
Operation and Maintenance
5-3). Up to 31 Gateways can be connected to a single I/O card in this manner.
B
C
D
Section 5: Operation and Maintenance
A
E
F
G
E Serial I/O Card
F. RS485 Bus
G. Smart Wireless Gateway
July 2015
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