ALLEN BRADLEY 1747-L551 PLC Processor

Setting Up the DH-485 Network
A–13
The table below shows wire/terminal connections for DH-485
connectors for Belden #9842.
For this Wire/Pair Connect this Wire To this Terminal
Shield/Drain Non-jacketed Terminal 2 – Shield
Blue/White
White with Blue Stripe
Blue with White Stripe
Cut back – no
connection ➀
Terminal 3 – (Common)
Wit White/Orange
White with Orange Stripe Terminal 4 – (Data B)
Orange with White Stripe Terminal 5 – (Data A)
➀ To prevent confusion when installing the communication cable, cut back the white with blue stripe
wire immediately after the the insulation jacket is removed. This wire is not used by DH-485.
Important: In Series A 1747-AIC, terminal 5 was called DATA B
and terminal 4 was called DATA A. In this case, use
terminal numbers only and ignore signal names DATA
B and DATA A. The internal circuitry of the Series A
is the same as Series B.
Grounding and Terminating the DH-485 Network
Only one of the link couplers at the end of the link must have
Terminals 1 and 2 of the network connector jumpered together. This
provides an earth ground connection for the shield of the
communication cable.
Link couplers at both ends of the network must have Terminals 5 and
6 of the link connectors jumpered together. This connects the
termination impedance (of 120Ω) that is built into each link coupler
as required by the DH-485 specification. See the figure below for
the proper jumpering.
End-of-Line Termination
Jumper
Jumper
6
5
4
3
2
1
Jumper
Belden #9842 Cable
1219 m (4000 ft) Maximum
6
5
4
3
2
1
Publication 1747-6.2