4WSD9R1203-3/4
© 2003 by B&B Electronics. All rights reserved.
International Headquarters:
707 Dayton Road P.O. Box 1040 Ottawa, IL 61350 USA
815-433-5100 Fax 433-5104
www.bb-elec.com [email protected] [email protected]
Westlink Commercial Park Oranmore Co. Galway Ireland
+353 91 792444 Fax +353 91 792445 www.bb-europe.com [email protected] [email protected]
Integrate
– Expand
– Simplify
B&B ELECTRONICS
PRODUCT INFORMATIONPRODUCT INFORMATIONPRODUCT INFORMATIONPRODUCT INFORMATION
Table 5: Switch settings for
RS-422 4-wire full-duplex
Switch # Position
1
RS-422
2
Echo On
3
4-wire
4
4-wire
Figure 2: RS-485 4-wire full-duplex diagram
RS-422 4-Wire Full-Duplex:
This communications mode is typically used for point-to-point communications over long
distances with better noise immunity than RS-232. Another common use would be as the
master in a master/slave configuration. The RS-422 driver and receiver are always
enabled to allow full-duplex communications. In order to do this there must be a pair of
wires dedicated to the driver, a pair dedicated to the receiver, and a ground reference
wire
i
for a total of 5 lines to operate properly. To set up for this mode, put switch 1 in the
RS-422 position, switch 2 in the Echo On position, and switches 3 and 4 in the 4-wire
position as shown in Table 5.
Figure 3: RS-422 4-wire full-duplex diagram
_________________________
i
If you are concerned about creating ground loops by connecting grounds of units together, please check into
B&B Electronics’ line of optically isolated RS-232 to RS-422/485 units such as the 485OT9L.
This product is Designed and Manufactured in the USA of domestic and imported components.
9-pin M/F cable
9-pin M/F cable
