RS-232
Connections
Manual Documentation Number: ESP904-0504
Appendix
57
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
A
A
P
P
P
P
E
E
N
N
D
D
I
I
X
X
A
A
:
:
R
R
S
S
-
-
2
2
3
3
2
2
C
C
O
O
N
N
N
N
E
E
C
C
T
T
I
I
O
O
N
N
S
S
ESP904 DB-9 Pin-outs in RS-232 Mode
RS-232
Signal Name
DTE RS-232 DB-9M
Pin
Carrier Detect
In
DCD
1
Receive Data
In
RXD
2
Transmit Data
Out
TXD
3
Data Terminal Ready
Out
DTR
4
Signal Ground
---
GND
5
Data Set Ready
In
DSR
6
Request To Send
Out
RTS
7
Clear To Send
In
CTS
8
Ring Indicator
In
RI
9
Figure 41. RS-232 Connections in a DB-9 Connector
RS-232
Connections
58
Appendix A
Manual Documentation Number: ESP904-0504
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 42. Straight-through (DTE to DCE) DB-9 to DB-9 Serial Cable
with RS-232 Signal Designations
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 43. Crossover (DTE to DTE) DB-9 to DB-9 Serial Cable with
RS-232 Signal Designations
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
