.Net and Cinterion Wireless Modules GmbH | Thales IoT Developer Community

Hi, Yhanks for your quickly reply, the exact module is CT 63 Terminal by CEP AG, My first Java application its app run on PC : the workflow of app : 1 openning port COM and wrote AT command for send SMS. Yes i can connect on the modem with an other client (ex : HyperTerm or putty .. and i can send AT command with this soft. With my .NET program i can connect at an other modem and send AT command, but with Cinterion Wireless Modules GmbH not working. I use USB interface and the modem is into peripherical modem into my computer on COM4 port. Are you using hardware flow control? YES I past my .net code : private void button1_Click(object sender, EventArgs e) { string number = txt_numTel.Text; string message = txt_message.Text; SerialPort _serialPort = new SerialPort("COM4", 9600, Parity.None, 8, StopBits.One); Thread.Sleep(1000); try { _serialPort.Open(); if (_serialPort.IsOpen) { MessageBox.Show("Communication avec le modem effective", "MODEM GSM TEST ...", MessageBoxButtons.OK); } } catch (Exception err) { MessageBox.Show(err.Message); } Thread.Sleep(1000); _serialPort.Write("AT+CMGF=1\r"); Thread.Sleep(1000); _serialPort.Write("AT+CMGS=\"" + number + "\"\r\n"); Thread.Sleep(1000); _serialPort.Write(message + "\x1A"); Thread.Sleep(1000); labelStatus.Text = "Status: Message sent"; _serialPort.Close(); } Thanks a lot for your help .