Rockwell Automation 2755 AdaptaScan Bar Code Readers - Manual (Page 52)

Installing the Wiring Base and Power Supply 3–17
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,
grounding, and termination. Refer to Data Highway /
Data Highway Plus / Data Highway DH485 Cable
Installation Manual (Publication No. 1770-6.2.2).
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.
SLC 5/04
Link Coupler
DH485 DH485
Reader Reader
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.
Line
Termination
TxA
TxB
RxA
RxB
Ground
Shield
RS-485/422
RS-485/422
RS-422
RS-422
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.
RS-485 and RS-422
Connections