Chris,

I've connected the device to my PC, using COM1 serial port.
I'm able to run HyperTerminal , send commands and see what the device
is returning. The configuration of hyperterminal, as you will know,
it's really simple:
just establish parity, stop bits, flow control, data bits, port name
and baudrate........and works!

I've also built a little example application in Winforms and
ReceiveData event is correctly fired after I've sent a command.
However, the value I read is not the value I expected. In all examples
they say "ReadExisting()" method is enough to read all data. This
method only gives me a "?" character, when I expect al least 20
characters.

Any other good way to read received data?

Thanks.

The cable you mention is just a synchronization cable via serial port
of the PC. It can substitute USB connection with the PC. I think this
it's different from providing the PDA a serial port. That's why I
bought the CF card. I also wrote a post for this in this newsgroup and
people advised me to buy the CF card.

Anyway, the cable you mention seems to have a female ending and I need
male ending. My device's cable ending is female, therefore I need male
ending for my cable.

Back to device-PC communication, to see wether communication
works......I send a command via hyperterminal and device switches
on.OK. Another command is sent and I got response.
If I do this, with the same configuration, from a Winforms application,
device is not switched on and always returns me "?", that seems to be
an error character.

This is my Winforms code (forget about Compact Framework for a moment),
see wether you can help me please:

private void ReceiveData(object sender, SerialDataReceivedEventArgs e)
{
           try
           {
                MessageBox.Show(serialPort.ReadExisting());
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
}

private void ErrorInSerialCommunication(object sender,
SerialErrorReceivedEventArgs e)
{
           MessageBox.Show("ERROR!");
}

private void button1_Click(object sender, System.EventArgs e)
{
           try
           {
               serialPort.BaudRate = 9600;
               serialPort.StopBits = StopBits.One;
               serialPort.Parity = Parity.None;
               serialPort.DataBits = 8;
               serialPort.PortName = "COM1";
               serialPort.Handshake = Handshake.None;
               serialPort.DataReceived += new
SerialDataReceivedEventHandler(ReceiveData);
               serialPort.ErrorReceived += new
SerialErrorReceivedEventHandler(ErrorInSerialCommunication);
               serialPort.Open();
               serialPort.RtsEnable = true;
               serialPort.DtrEnable = true;
               serialPort.Write("DM");
           }
           catch (Exception exc)
           {
               MessageBox.Show(exc.Message);
           }
       }

I understand port must leave opened after sending the command.
ReceiveData event is fired but as I've said, always returns "?"
character.
I'm using Write() method instead of WriteLine(), because in
Hyperterminal don't need any return character. Just typing "DM", device
gets ready. With this example, not.

Please tell me if you see something suspicious. Thanks very much.