Emerson 1410 - Rs-485

18
Reference Manual
00809-0200-4410, Rev BC
Mounting and Connection
July 2017
Mounting and Connection
Figure 3-5. Gateway Terminal Block
A. 5-screw terminal block
B. 24 VDC (nominal) power input
C. Serial Modbus
®
Ethernet connections should use Cat5e shielded cable to connect to an Ethernet hub, switch, or router.
The maximum cable length should not exceed 328 ft (100 m).
3.4.3 RS-485
The Gateway can be ordered with an optional RS-485 (serial) connection (Figure 3-6 on page 18).
Modbus terminals are labeled A and B on the wiring diagram. This connection is used to communicate
Modbus RTU on an RS-485 data bus.
Use 18 AWG single twisted shielded pair wiring to connect the Gateway to the RS-485 data bus. The total
bus length should not exceed 4000 ft (1220 m). Connect the Tx - (negative, receive) wire to terminal A
and the Rx + (positive, transmit) wire to terminal B. The wiring shield should be trimmed close and
insulated from touching the Gateway enclosure or other terminations.
If the existing data bus uses a 4-wire Full Duplex configuration, see Figure 3-6 to convert to a 2-wire Half
Duplex configuration.
Figure 3-6. Convert from Full to Half Duplex
+
-A+B-
S
Power
Reset
A
BC
Tx
Rx
Tx
Rx
(A)
(B)