private void btn_send_Click(object sender, EventArgs e) { dataToWrite = textBox1.Text; UInt32 numBytesWritten = 0; // Note that the Write method is overloaded, so can write string or byte array data ftStatus = myFtdiDevice.Write(dataToWrite, dataToWrite.Length, ref numBytesWritten); if (ftStatus != FTDI.FT_STATUS.FT_OK) { MessageBox.Show("Somthing wrong happend!"); } Reciever.RunWorkerAsync(); }