Black Box PC↔422/485 Instructions Manual page 9

PC ↔ 422/485 SERIAL INTERFACE
PC-422/485 CARD
Figure 2-2. An RS-485 multipoint application.
PC-422/485 CARD
Figure 2-3. An RS-485 two-wire half-duplex application.
Table 2-1. The Pinout of the Card's DB25 Connector (J2)
Signal
GND
RX+ (RX B)
RX– (RX A)
TX+ (TX B)
TX– (TX A)
8
RX
TX
TX
RX
Echo is not disabled in 2-wire operation.
Name
Ground
Receive Positive
Receive Negative
Transmit Positive
Transmit Negative
NOTE
Pin
7
12
13
24
25
TX
RS-485 DEVICE
RX
TX
RS-485 DEVICE
RX
RS-485 DEVICE
Direction
None
Input to card
Input to card
Output from card
Output from card