1. Straight-through cables for RJ-45, DB-25, and DB-9 are:
RJ-45 DB-25 DB-9
------ ------ ------
1 RI ----- 22 RI ----- 9 RI Ring Indicator
2 DSR ----- 6 DSR----- 6 DSR Data Set Ready
3 RTS ----- 4 RTS----- 7 RTS Request to Send
4 CGnd----- 1 CGnd---- NA Chassis ground
5 TxD ----- 2 TxD----- 3 TxD Transmit Data
6 RxD ----- 3 RxD----- 2 RxD Receive Data
7 SGnd----- 7 SGnd---- 5 SGnd Signal Ground
8 CTS ----- 5 CTS----- 8 CTS Clear to Send
9 DTR ----- 20 DTR----- 4 DTR Data Terminal Ready
10 CD ----- 8 CD ----- 1 CD Carrier Detect
2. Null Modem cable RJ-45 & DB-25.
RJ-45 DB-25
------ ------
5 TxD ----- 3 RxD
6 RxD ----- 2 TxD
3 RTS ----- 5 CTS
8 CTS ----- 4 RTS
+- 6 DSR
9 DTR ---+- 8 CD
10 CD -+--- 20 DTR
2 DSR -+
1 RI ----- 22 RI
7 SGnd----- 7 SGn
4 CGnd----- 1 CGn
3. Null Modem cable RJ-45 & DB-9.
RJ-45 DB-9
------ ------
5 TxD ----- 2 RxD
6 RxD ----- 3 TxD
3 RTS ----- 8 CTS
8 CTS ----- 7 RTS
+- 6 DSR
9 DTR ---+- 1 CD
10 CD -+--- 4 DTR
2 DSR -+
1 RI ----- 9 RI
7 SGnd----- 5 SGn
4 CGnd----- n/a