3COM CORPORATION

PHONE LINK 300

Card Type                Modem (asynchronous)
Chip Set                 U.S. Robotics
Maximum Data Rate        300bps
Data Bus                 External
Data Modulation Protocol WE 103/113

                                                                      54167

                                CONNECTIONS

         Function           Label             Function             Label

  Line out                       CN1       DC power                 CN4

  Line in                        CN2       Power switch             SW1

  RS-232/422                     CN3

                        USER CONFIGURABLE SETTINGS

                      Setting                         Label      Position

  Originate enabled                                   SW2/A        Off

  Answer enabled                                      SW2/A        On

  Local echo disabled                                 SW2/B        Off

  Local echo enabled                                  SW2/B        On

                             DIAGNOSTIC LED(S)

   LED      Color    Status                    Condition

    ON       Red       On                     Power is on

    ON       Red      Off                    Power is off

    CD       Red       On               Carrier signal detected

    CD       Red      Off             Carrier signal not detected

    TS       Red       On                  Test mode enabled

    TS       Red      Off                 Test mode disabled

    SD       Red       On             Modem is transmitting data

    SD       Red      Off           Modem is not transmitting data

    RD       Red       On               Modem is receiving data

    RD       Red      Off             Modem is not receiving data

                       MISCELLANEOUS TECHNICAL NOTES

            Note: Transmit level adjustment, this can be made by looking
            under the Phone Link for a screw potentiometer. Turning the
            screw clockwise will increase transmit level and turning the
            screw counterclockwise will decrease transmit level. This
            should be done if you are experiencing errors receiving data
            or the remote receiving data from the Phone Link.

            Diagram not available.