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V.24

An ITU standard (1964) that defines the functions of all circuits for the RS-232 interface. It does not describe the connectors or pin assignments; those are defined in ISO 2110. In the U.S., EIA-232 incorporates the control signal definition of V.24, the electrical characteristics of V.28 and the connector and pin assignments defined in ISO 2110. See RS-232.



RS-232

(Recommended Standard-232) A TIA/EIA standard for serial transmission. Although employed for numerous other purposes, the RS-232 serial port was widely used on earlier personal computers prior to USB (see serial port). The RS-232 cable limitation of 50 feet can be extended to several hundred feet with high-quality cable.

Although RS-232 defines the signals for 25 lines, many applications use less than a dozen, which is why both DB-25 and DB-9 connectors are used. RS-232 transmits positive voltage for a 0 and a negative voltage for a 1. In 1984, RS-232 was officially renamed TIA/EIA-232-E. See RS-232/485.


          Pin Settings for Plug
       (Reverse order for socket.)
  ______________________________________
  1  2  3  4  5  6  7  8  9  10 11 12 13
   14 15 16 17 18 19 20 21 22 23 24 25

           _________________
             1  2  3  4  5
               6  7  8  9


 25 pin                        9 pin

  1 - PG   Protective ground
  2 - TD   Transmitted data     3
  3 - RD   Received data        2
  4 - RTS  Request to send      7
  5 - CTS  Clear to send        8
  6 - DSR  Data set ready       6
  7 - SG   Signal ground        5
  8 - CD   Carrier detect       1
  9 - + voltage (testing)
 10 - - voltage (testing)
 11 - 
 12 - SCD  Secondary CD
 13 - SCS  Secondary CTS
 14 - STD  Secondary TD
 15 - TC   Transmit clock
 16 - SRD  Secondary RD
 17 - RC   Receiver clock
 18 - 
 19 - SRS  Secondary RTS            9 pin
 20 - DTR  Data terminal ready      4
 21 - SQD  Signal quality detector
 22 - RI   Ring indicator           9
 23 - DRS  Data rate select
 24 - XTC  External clock
 25 - 





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Before/After Your Search Term
BeforeAfter
V-RAMV.25
v-regV.25bis
V SeriesV.26
V.110V.26bis
V.120V.26ter
V.17V.27
V.21V.27bis
V.22V.27ter
V.22bisV.28
V.23V.29

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