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DB9 to RJ11 Connector Pinout - AllPinouts

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From [1] is a interface for RS-232 from DB-9S (Female) to RJ11 to telephone cable to RJ11 to DB-9P (Male). It is not known whether this is any type of standard. Note that if this is accidentally connected to a telephone, then one telephone wire is grounded, and TXD and RXD are no connect. Everything should survive.

6 PIN RJ11, RJ14, RJ25 FEMALE CONNECTOR
6 pin RJ11, RJ14 female connector at the phone and wallet socket (Jack).


6 PIN RJ11, RJ14, RJ25 MALE CONNECTOR
6 pin RJ11, RJ14 male connector at the cable (Plug).

DB9S (female pins) to jack:

RJ11 DB9S Function
1 NC -
2 2 RXD
3 5 GND
4 NC -
5 3 TXD
6 NC -

DB9p (male pins) to jack:

RJ11 DB9P Function
1 NC -
2 3 TXD
3 NC -
4 5 GND
5 2 RXD
6 NC -

Phone cable, please note that this is a crossover cable, with pins 1 and 6 not used:

RJ11 RJ11
1 or NC 6 or NC
2 5
3 4
4 3
5 2
6 or NC 1 or NC

Here is a variation that is also used. It provides two grounds:

DB9S (female pins) to jack:

RJ11 DB9S Function
1 NC -
2 2 RXD
3 5 GND
4 5 GND
5 3 TXD
6 NC -

DB9p (male pins) to jack:

RJ11 DB9P Function
1 NC -
2 3 TXD
3 5 GND
4 5 GND
5 2 RXD
6 NC -


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