B&B Electronics 3PCIOU4 - Manual - Manual (Page 52)

Connector Pinouts
B-2 Appendix B Document Number 3PCI-0712m
RS-422/485 Pinouts
Name Description Direction DB-9M
Pin
RDA( ) Receive Data A (-) Input 1
TDB(+) Transmit Data B (+) Output 2
TDA( ) Transmit Data A (-) Output 3
GND Signal Ground ------ 5
RDB(+) Receive Data B (+) Input 9
Figure 29. RS-422/485 Signal Designations and DB-9 Pinout
With 2-wire RS-485 mode operation, your connection cable must jumper TDA(-) to
RDA(-) and TDB(+) to RDB(+). Connect from TDA(-) and TDB(+) to the Data A( ) and
Data B(+) wires of your RS-485 network.
Note: Refer to Chapter 2 for example connections.
Note that the EIA RS-422 Specification labels data lines with an "A" and "B" designator.
Some RS-422 equipment uses a " " and "+" designator. In almost all cases, the "A" line
is the equivalent of the " " line and the "B" line is the equivalent of the "+" line.
Note: For more information on RS-422 communications refer to the
B&B Electronics RS-422/485 Application Note at www.bb-elec.com
Figure 30. 2-Wire RS-485 Wiring Diagram