RS232 interface

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The serial port can be used by NuMorse to operate hardware devices such as a transmitter or flashing lamp. The RS232 RTS and DTR lines are used and you can select one of two modes. One line will toggle up and down as the code elements are sent while the other line switches at character rate. You choose which does which. The latency setting in this window allows a short pause before code element switching starts. This is useful if you need to switch a rig from rx to tx before sending code. The enabled box is a master switch for this feature.


You may need to build an interface circuit to drive hardware devices from your PC, or your transceiver may already have a compatible built-in serial interface.


9-pin or 25-pin connectors are used for the serial ports on most PCs. If a serial connector is not provided on the PC then it may be possible to use a USB-serial interface unit. Pinout details for the RTS and DTR lines are shown below.


RS-232 - DB9 serial male connector





Pin Assignments for DB9 serial connector


    1     DCD     Data carrier (line signal) detect

    2     RXD     Receive data

    3     TXD      Transmitted data

    4     DTR     Data terminal ready

    5     GND     (Signal) ground

    6     DSR     Data set ready

    7     RTS     Ready/request to send

    8     CTS     Clear to send

    9     RI         Ring indicator


RS-232 - DB25 serial male connector




Pin Assignments for DB25 serial connector


   1                 Shield - chassis/frame protective ground

    2     TXD      Transmitted data

    3     RXD     Receive data

    4     RTS     Ready/request to send

    5     CTS     Clear to send

    6     DSR     Data set ready

    7     GND     (Signal) ground

    8     DCD     Data carrier (line signal) detect

    9                 Reserved for testing - positive voltage

    10               Reserved for testing - negative voltage

    11               Unassigned

    12   SCF     Secondary received carrier (line signal) detect

    13   SCB     Secondary clear to send

    14   SBA     Secondary transmitted data

    15   DB       Transmission signal element timing (clock)

    16   SBB     Secondary received data

    17   DD       Receiver signal element timing (clock)

    18               Unassigned

    19   SCA     Secondary request to send

    20   DTR     Data terminal ready

    21   CG       Signal quality detector

    22   RI         Ring indicator

    23   CH/CI   Data signal rate selector

    24   DA       External transmit signal element timing (clock)

    25               Test mode