Esr90, Db-9, Out in – B&B Electronics ESR904 - Manual User Manual
Page 85: Rs-485f, Four, Wire, Full duplex, Esr901, Erminal, Lock
RS-485 Connections
Manual Documentation Number: ESR90x-5012m
Appendix C
75
B&B Electronics Mfg Co Inc – 707 Dayton Rd - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 – www.bb-elec.com
B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445 – www.bb-europe.com
ESR90x DB-9 Pin-out in RS-485F (four-wire, full duplex) 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 54. RS-422 Connections in a DB-9 Connector
N
N
o
o
t
t
e
e
:
:
Some RS-485 devices are marked opposite the RS-485 standard, which
defines the Data B line as positive relative to Data A during a Mark state before
enabling the transmitter, and after transmitting before tri-stating. If an RS-485
device does not respond, try swapping the Data B and Data A lines.