43
Chapter 5
For DTE to DCE connections, use straight-through cable (i.e., you don't
have to reverse lines 2 and 3, lines 4 and 5, and lines 6 and 20 since, in
general, the DCE RS-232 interfaces are reversed themselves).
Therefore, if you are not using CTS, RTS, DSR, DTR and DCD signals,
please short pins 4 and 5 together, and please short pins 6, 8, and 20
together.
Table 5.6: Modem Connections
DB25 Male
Modem (DCE)
Pin
Signal
Pin
Signal
2
TxD
2
RxD
3
RxD
3
TxD
4
RTS
4
CTS
5
CTS
5
RTS
6
DSR
6
DTR
7
GND
7
GND
20
DTR
20
DSR
8
DCD
8
DCD
Table 5.7: Terminal without Handshake
DB-25 Male
Terminal, PC (DTE)
Pin
Signal
Pin
Signal
2
TxD
3
RxD
3
RxD
2
TxD
4
5
RTS —
CTS —
7
GND
7
GND
6
20
8
DSR —
DTR —
DCD —
