muLOGIC RSA-1 20 Series - Cross Cables for Connection to a Device with RS-232 DCE Port

User Guide – Appendix Industrial remote access router - RSA-series
Page 24
Cross Cables for connection to a device with RS-232 DCE port.
The RS-232 connector of the unit is of the type DCE.
It can connect directly to a DTE type of serial port using a straight cable.
For connection to another DCE port, a “cross cable” is needed.
Note:
An RS-232 DCE port (modem) usually has a female DB9 or DB25 connector.
An RS-232 DTE port (PC) usually has a male DB9 or DB25 connector.
The following tables show the wiring of such cables.
DB9 to DB9 DCE-DCE cross cable
DB9 to DB25 DCE-DCE cross cable
Connector A
(DB9 Male)
Connector B
(DB9 Male)
Pin
Signal
Direction
Pin
Signal
1
DCD (output)

4
DTR (input)
2
RxD (output)

3
TxD (input)
3
TxD (input)

2
RxD (output)
4
DTR (input)

1
DCD (output)
5
Signal ground
--
5
Signal ground
6
DSR (not used)
6
DSR(not used)
7
RTS (input)

8
CTS (output)
8
CTS (output)

7
RTS (input)
9
Ring (not used)
9
Ring (not used)
Connector A
(DB9 Male)
Connector B
(DB25 Male)
Pin
Signal
Direction
Pin
Signal
1
DCD (output)

20
DTR (input)
2
RxD (output)

2
TxD (input)
3
TxD (input)

3
RxD (output)
4
DTR (input)

8
DCD (output)
5
Signal ground
--
7
Signal ground
6
DSR (not used)
6
DSR(not used)
7
RTS (input)

5
CTS (output)
8
CTS (output)

4
RTS (input)
9
Ring (not used)
22
Ring (not used)