Rs-232 straight-through cable connections, Rs-232 crossover (null modem) cable connections – B&B Electronics ESP904 - Manual User Manual
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RS-232 Connections
68
Appendix A
Manual Documentation Number: ESP904-4513m
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - 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
RS-232 Straight-through Cable Connections
In the RS-232 mode, the ESP904’s ports are configured as DTEs like a
computer. If the device connected to the ESP904 is configured as a DCE use
a straight through cable wired as shown below:
Figure 58. Straight-through DB-9 to DB-9 RS-232 Serial Cable
RS-232 Crossover (null modem) Cable Connections
When connecting to a PC or another DTE device, use a crossover cable (also
called a null modem cable).
Figure 59. Crossover DB-9 to DB-9 RS-232 Serial Cable
RS-232 Signal Names
DB-9
Pin#
Connections
DB-9
Pin#
Signal
Carrier Detect
CD
1
1
CD
Receive Data
RD
2
2
RD
Transmit Data
TD
3
3
TD
Data Terminal Ready
DTR
4
4
DTR
Signal Ground/Common
GND
5
5
GND
Data Set Ready
DSR
6
6
DSR
Request to Send
RTS
7
7
RTS
Clear to Send
CTS
8
8
CTS
Ring Indicator
RI
9
9
RI
RS-232 Signal Names
DB-9
Pin#
Connections
DB-9
Pin#
Signal
Carrier Detect
CD
1
1
CD
Receive Data
RD
2
2
RD
Transmit Data
TD
3
3
TD
Data Terminal Ready
DTR
4
4
DTR
Signal Ground/Common
GND
5
5
GND
Data Set Ready
DSR
6
6
DSR
Request to Send
RTS
7
7
RTS
Clear to Send
CTS
8
8
CTS
Ring Indicator
RI
9
9
RI