Technical data
RS-422 Connections
Manual Documentation Number: Appendix B 73
Black Box Corporation - 1000 Park Drive - Lawrence, PA 15055-1018
www.blackbox.com -- Tech Support and Ordering: 724-746-5500 - Fax: 724-746-0746
A
A
P
P
P
P
E
E
N
N
D
D
I
I
X
X
B
B
:
:
R
R
S
S
-
-
4
4
2
2
2
2
/
/
4
4
8
8
5
5
C
C
O
O
N
N
N
N
E
E
C
C
T
T
I
I
O
O
N
N
S
S
2 Port Serial Server DB-9 Pin-out in RS-422 Mode
RS-422
Signal Name
Direction
RS-422
DB9M
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
Figure 51. RS-422 Connections in a DB-9 Connector
RS-422 Connections
74 Appendix B Documentation Number: LES40xA-1105m
Black Box Corporation - 1000 Park Drive - Lawrence, PA 15055-1018
www.blackbox.com -- Tech Support and Ordering: 724-746-5500 - Fax: 724-746-0746
1 Port Serial Terminal Block Pin-out in RS-422 Mode
G
N
D
C
T
S
/
T
X
-
T
X
/
T
X
+
R
X
/
R
X
+
R
T
S
/
RX
-
1
2
3
4
5
Signal Name RS-422 Direction Terminal
Signal Ground GND --- 1
Transmit Data (-) TXD(-) Out 2
Transmit Data (+) TXD(+) Out 3
Receive Data (+) RXD(+) In 4
Receive Data (-) RXD(-) In 5
Figure 52. 1 Port Serial Server Terminal Block Pinout in RS-232
Mode
In the RS-422 mode, TXD lines are outputs and RXD lines are inputs.
Connect the Serial Server TXDB(+) line to the RXDB(+) line of the serial
device, and the Serial Server TXDA(-) to the RXDA(-) of the serial device.
If Flow Control is set for RTS/CTS, connect the Serial Server RTSB(+) to
CTSB(+) of the serial device and the Serial Server RTSA(-) line to the
CTSA(-) of the serial device. Connect from the Serial Server CTSB(+) line to
the RTSB(+) of the serial device and from the Serial Server CTSA(-) line to
the RTSB(+) line of the serial device.
If connecting to Receive Only RS-422 devices, connect from the Serial
Server TXDB(+) and TXDA(-) lines to the receive pairs on all serial devices.
Ground is signal ground and provides a common mode reference for the RS-
422 Receiver and Transmitters.