NAME
    Write -- send output to serial port

FUNCTION
    This command causes a stream of characters to be written out
    the serial port. The number of characters is specified in
    io_Length, unless -1 is used, in which case output is sent until
    a null(0x00) is encountered.

IO REQUEST
    io_Message      must have mn_ReplyPort initialized
    io_Device       set by opendevice
    io_Unit         set by opendevice
    io_Command      CMD_WRITE
    io_Flags        Set IOF_QUICK to try quick I/O
    io_Length       number of characters to transmit, or if set
                    to -1 transmit until null encountered in buffer
    io_Data         pointer to block of data to transmit

RESULTS
    Error -- if the Write succeded, then io_Error will be null.
        If the Write failed, then the io_Error will be non-zero.

SEE ALSO
    serial.device/sdcmd_setparams