B&B Electronics Optically Isolated Single Port PCI Bus CE Appendix B RS-232 & RS-422/485 Pinouts

Appendix B: RS-232 & RS-422/485 Pinouts

Table 1: RS-232 Pinouts

Name	Description	Direction	DB25M
			Pin
Shield	Shield	------	1
TD	Transmit Data	Output	2
RD	Receive Data	Input	3
RTS	Request to Send	Output	4
CTS	Clear to Send	Input	5
DSR	Data Set Ready	Input	6
GND	Signal Ground	------	7
DCD	Data Carrier Detect	Input	8
DTR	Data Terminal Ready	Output	20

Table 2: RS-422/485 Pinouts

Name	Description	Direction	DB25M
			Pin
Shield	Shield	------	1
TD (A) −	Transmit Data A	Output	2
RD (A) −	Receive Data A	Input	3
GND	Signal Ground	------	7
TD (B) +	Transmit Data B	Output	14
RD (B) +	Receive Data B	Input	16

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.

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 our free RS- 422/485 Application Note (available on our websites).

Documentation Number 3PCIOSD1x-3903m Manual Appendix B B-1 B-2 Appendix B Documentation Number 3PCIOSD1x-3903m Manual

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