1                       ____________________________
     System End       __|__________            | System End  |    Modem End |
                     |  . . . . .  |           | HD-15  _____|____    DB-37 |
                   6-- . . . . .   |           | pin   |  Signal  |     pin |
                      \ . . . . . /            |_______|__________|_________|
                       \|_______|/             |  1     RxD- | RD-       6  |
                        |       |              |  2     RxD+ | RD+      24  |
                       11       15             |  4     RxC- | RT-       8  |
     1      Modem End                    19    |  5     RxC+ | RT+      26  |
    _|___________________________________|_    |  6     TxD- | SD-       4  |
   | . . . . . . . . . . . . . . . . . . . |   |  7     TxD+ | SD+      22  |
    \ . . . . . . . . . . . . . . . . . . /    |  9     TxC- | ST-       5  |
      |_________________________________|      | 10     TxC+ | ST+      23  |
     20           Male DB-37            37     | 12    ShGnd | ShGnd    19  |
                                               |_____________|______________|

         <=1000ft 28 AWG - max16pF/f -  type Belden 9806 or equivalent
          >1000ft 24 AWG - max16pF/f  - type Belden 9831 or equivalent


   __________________           ______________
  | 128-Port        1|----NG---|EIA-422 Modem |------ -.
  | Adapter         2|         |______________|        |
  |_______          _|                                 |
          ||||||||_|         .----- TEL Lines   - - - -'
                             |
                             |   _____________
                             '--|EIA-422 Modem|--NH------. .--------.
                                |_____________|          | |        |
                                                        _|_|_      _|_T_
                                                       |Node1|    |Node2|
                                                       |_____|    |_____|