Sample C# Program for Communicating with the TReX and TReX Jr

The following program, written using Visual C# 2008, provides a simple example of how you can send and receive data from the TReX or TReX Jr using Microsoft’s visual C# and your computer’s serial port. It sends the TReX a “get signature” command when the Get Signature button is pressed and displays the response from the TReX in the text box.

The sendCommandPacket method is a simplified version of the one used by the TReX Configurator utility (297k zip).

You can download the project files here: trex.zip (60k zip). Don’t forget to configure the serialPort1 object’s portName property for the COM port to which your TReX or TReX Jr is connected.

Sample C# TReX program: configuring the SerialPort object.

using System;
using System.Windows.Forms;

namespace TReX
{
    public partial class Form1 : Form
    {
        int deviceNum = 7;  // default device number for the TReX and TReX Jr
        bool serialEcho;    // does the TReX echo everything you transmit? (true for RS-232)
        byte[] buffer;     // array to hold our command packets and received data

        public Form1()
        {
            InitializeComponent();
            buffer = new byte[32];
        }

        private bool sendCommandPacket(byte[] packet, int sendBytes, int readBytes, ref string str)
        {
            /* This function transmits the specified command packet and then waits to receive
             * the specified number of bytes in response.  Bytes to transmit are provided via the
             * 'packet' array, and received bytes are stored in the 'packet' array.
             * It blocks execution until the desired number of bytes have been received from the
             * the TReX or until the serial read times out (150 ms).
             *   packet - an array of bytes to transmit to the TReX; when the function is through,
             *            this array will contain any bytes received from the TReX, so the size of
             *            this array must be greater than or equal to Max(sendBytes, readBytes)
             *   sendBytes - the number of bytes in the command packet
             *   readBytes - the number of bytes to try to receive from the TReX in response
             *   str - a string that contains information about what was sent and received;
             *         used for debugging/feedback purposes
             */

            int i;
            str = "";

            try
            {
                // if there are any unread bytes in the read buffer, they are junk
                //  read them now so the buffer is clear to receive anything the TReX
                //  might send back in response to the command
                while (serialPort1.BytesToRead > 0)
                    serialPort1.ReadByte();

                str += " TX={ ";
                if (expandedProtocolCheckBox.Checked)
                {
                    for (i = sendBytes - 1; i >= 0; i--)
                        packet[i + 2] = packet[i];
                    packet[0] = 0x80;
                    packet[1] = (byte)deviceNum;
                    packet[2] -= 0x80;     // clear MSB of command byte
                    sendBytes += 2;
                }

                for (i = 0; i < sendBytes; i++)
                    str += packet[i].ToString("X2") + " ";
                serialPort1.Write(packet, 0, sendBytes);
                if (serialEcho)
                {
                    str += "};  Echo={ ";
                    for (i = 0; i < sendBytes; i++)
                        str += serialPort1.ReadByte().ToString("X2") + " ";
                }
                str += "};  RX={ ";
                for (i = 0; i < readBytes; i++)
                {
                    packet[i] = (byte)serialPort1.ReadByte();
                    str += packet[i].ToString("X2") + " ";
                }
                str += "}";
            }

            catch (Exception)
            {
                str += " *TIMEOUT*";
                return false;
            }

            return true;
        }


        private void signatureButton_Click(object sender, EventArgs e)
        {
            try
            {
                logTextBox.Text = "";
                serialPort1.Open();
                buffer[0] = 0xFF;
                serialPort1.Write(buffer, 0, 1);   // send the null command
                try
                {
                    int data = serialPort1.ReadByte();   // look for an echo
                    if (data == 255)
                        serialEcho = true;  // we get here if we are using RS-232
                }
                catch (TimeoutException)
                {
                    serialEcho = false;     // we get here if we are using TTL serial
                }

                // read the device signature
                string str = "";
                buffer[0] = 0x81;
                if (!(sendCommandPacket(buffer, 1, 7, ref str)))
                    logTextBox.Text += "failure\r\n" + str;
                else
                {
                    logTextBox.Text += "" + str + "\r\n";
                    for (int i = 0; i < 7; i++)
                        logTextBox.Text += (char)buffer[i];
                }
            }
            catch (Exception)
            {
                logTextBox.Text += "Exception!";
            }
            if (serialPort1.IsOpen)
                serialPort1.Close();
        }
    }
}