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RS-485 and RS-422
Connections
The wiring base has an RS-485/RS-422 terminal block for
point-to-point or network communications. Up to 32 devices can be
installed on a single DH485 network.
Important: The DH485 network cable requires proper shielding,
Network or Point-to-Point
Allen-Bradley offers a variety of devices that support RS-485 or
RS-422 communications. One of the more common RS-485 network
types is an SLC DH485 network.
Reader
DH485
Use the link coupler (Catalog No. 1747-AIC) when the distance
between the Reader and SLC is greater than 50 feet (15.2 meters).
The Reader can connect directly to another RS-485/RS-422 device.
The connections for both network and point-to-point are the same.
RS-485/422
TxA
RS-485/422
TxB
RS-422
RxA
RS-422
RxB
Ground
Shield
Line Termination
The end devices on an RS-422/RS-485 network must be terminated.
A termination switch is provided. Only the end devices, on each
end of a network, should be terminated.
Installing the Wiring Base and Power Supply
grounding, and termination. Refer to Data Highway /
Data Highway Plus / Data Highway DH485 Cable
Installation Manual (Publication No. 1770-6.2.2).
SLC 5/04
Link Coupler
3–17
Reader
DH485
Line
Termination
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