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Serial Connector Pinouts

Tuesday, November 25, 2008

From time to time I have to make serial connector adapters to get from DB9 to RJ45. Many devices (cisco, lantronix, etc.) use RJ45 connections for serial ports, many others use DB9 connections. This simple pinout works with an RJ45/DB9 connector to make the connection, these connectors are available at any decent electronics shop for about $3, you just have to push the pins into the right holes. The sweet thing about this is you can pick straight or null-modem by using either a straight cable or a telco-roll cable (not ethernet roll, telco-roll reverses all the conductors and usually is used with flat satin cable, just flip the cable over before putting on the rj45 head so on one end blue is on the left, on the other end white is on the left).

DB9 Pin -> Color -> Signal
1 -> Orange -> DCD
2 -> Black -> RX
3 -> Yellow -> TX
4 -> Brown -> DTR
5 -> Red -> SGND
6 -> no connection
7 -> White -> RTS
8 -> Blue -> CTS
9 -> no connection
- -> Green -> no connection