RS232C pinout

== 25pin DIN ==
   ---------

PIN     USE                     IMPORTANT ONES

1       protGND                 pGND
2       TxD                     TxD
3       RxD                     RxD
4       RTS                     RTS
5       CTS                     CTS
6       DSR                     DSR
7       sigGND                  sGND
8       carr. detec.
9       reserved
10      reserved
11      n/c
12      sec carr.detec.
13      sec CTS
14      secTxD
15      Txclock(DCE)            dceTxC
16      secRxD
17      Rxclock                 RxC
18      n/c
19      secRTS
20      DTR                     DTR
21      sig. detec.
22      bell detec.             bell
23      baud rate sel.          baud
24      Txclock (DTE)           dteTxC
25      n/c


== RJ-11 ==
   -----

        1       n/c
        2       Tx
        3       DTR
        4       GND
        5       Rx
        6       n/c


== DB9 ==
   ---

        1       ?
        2       Tx
        3       Rx
        4       DTR
        5       GND
        6       ?
        7       n/c
        8       ?
        9       n/c