B&B Electronics manual Table B.3 RS-422/485 Pinouts Name Description Direction

Table B.3: RS-422/485 Pinouts

Name	Description	Direction	DB9M
			Pin
RD(A) −	Receive Data A	Input	1
TD(B) +	Transmit Data B	Output	2
TD(A) −	Transmit Data A	Output	3
GND	Signal Ground	------	5
RD(B) +	Receive Data B	Input	9

With 2-wire RS-485 mode operation, your connection cable must jumper TD(A) to RD(A) and TD(B) to RD(B). Connect from TD(A) and TD(B) to the Data A(−) and Data B(+) wires of your RS-485 network.

See 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. More information on RS-422 communications can be found in the B&B Electronics RS-422/485 Application Note (available on our website).

B-2 Appendix B Documentation Number 3PCIO1-0903 Manual

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