RJ11-RS232  

      RJ11-RJ45










diagram RJ11 to rs232
diagram RJ11 to rs232

RJ11 - RS232


The RJ11 is interesting, because the manufacturer has chosen to have a symmetrical arrangement of pins, just like with the systems DECconnect MMJ connector and the RJ45 in the Yost standard.
A symmetrical pin layout allows to connect two DTE, data terminal ()) directly without using a modem or other DCE data communication equipment.


The original wiring RS232 was developed for 25 pins.
The vast majority of applications RS232 use only 3 links : TX, RX and GND.

9 pins RS232 connectors are commonly used.
In mixed applications, a 9-to-25 converter can be used to plug in different sizes.
Two other contacts of signal, RTS and CD are sometimes used when interfacing to modems or RJ11.



RJ11 DB9
1 1
4 5
5 3
3 2






For a RJ11 connection to connection RS232 since one taken DB25 :







DB9 DB25 SIGNAL INPUT/OUTPUT
1 8 DCD (DATA DETECTED) ENTRANCE 1
2 3 RXD (RECEIVING) ENTRY
3 2 TXD (TRANSMITTER) OUTPUT
4 20 DTR (DATA READY) OUTPUT 1
5 7 SG (SIGNAL GROUND) .
6 6 DSR (DATA SET) ENTRANCE 1
7 4 RTS (REQUES TO SEND) OUTPUT 1
8 5 (RESET TO SEND) CTS ENTRY 1
9 22 RI (MODEM) (RING INDICATOR) ENTRANCE 1




Adapter RJ11 to RS232
Adapter RJ11 to RS232

Presentation of the telephone connectors







POSITION RJ25 RJ14 RJ11 TWISTED PAIR RECEPTION/TRANSMISSION COLOR TWISTED PAIR COLORS RJ25
1 1 -- PAIR 3 TRANSFER WHITE/GREEN WHITE/GREEN
2 2 1 - 2 PAIR TRANSFER WHITE/ORANGE WHITE/ORANGE
3 3 2 1 1 PAIR RECEPTION BLUE BLUE/WHITE
4 3 2 - 1 PAIR TRANSFER WHITE/BLUE WHITE/BLUE
5 5 4 - 2 PAIR RECEPTION ORANGE ORANGE/WHITE
6 6 -- PAIR 3 RECEPTION GREEN GREEN/WHITE




adapter RJ11 to rs232
adapter RJ11 to rs232

Table of pin RJ11 RS232 connections







RJ11 DB9
1 1
4 5
5 3
3 2




Interior view
Interior view

Adapters


Full RS232 mode, six available pins are assigned to the most used RS232 signals. Pins 1 and 6 are however reassigned to lines A and B when the port is used in RS485 mode.
These pins are normally used for the DTR, the terminal ready data and the DSR, willing to establish data signal.

On some models of the PLC, it is possible to mix the RS232 and RS485 communication. When the DSR and DTR signals are not used, the two pins can be used for simultaneous RS485 communication.

RJ11 to RS232 adapters are technically simple.

They are a little expensive, found on the Web or in the specialized shops.