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Appendix B: RS-422/485 Connections
Appendix B. RS-422/485 Connections
B.1 2- and 4-Port Serial Server DB9 Pinout in RS-422 Mode
Figure B-1. DB9 connector.
Table B-1. RS-422 connections in a DB9
connector.
RS-232 Signal Name Direction RS-422 DB9 M Pin
Receive Data A (-) In RXDA (-) 1
Receive Data B (+) In RXDB (+) 2
Transmit Data B (+) Out TXDB (+) 3
Transmit Data A (-) Out TXDA (-) 4
Signal Ground — GND 5
Clear To Send A (-) In CTSA (-) 6
Clear To Send B (+) In CTSB (+) 7
Request To Send B (+) Out RTSB (+) 8
Request To Send A (-) Out RTSA (-) 9