LibUsbDotNet 2.2.8
Read Write (Polling)
LibUsbDotNet on SourceForge

This example only works with custom usb hardware. Using this example on a usb device it was not designed for could be catastrophic! To meet the requirements, your usb hardware must implement loopback functionality in Config 1, Interface 0, Endpoints 0x01 and 0x81.

Read Write (Polling): Console Application Description
  1. Opens a USB device by vendor and product id.

  2. Opens a UsbEndpointReader class for reading.

  3. Opens a UsbEndpointWriter class for writing.

  4. Writes all command line text to Ep01

  5. Reads and displays usb device output from Ep01

Example
CopyC#
using System;
using System.Text;
using System.Text.RegularExpressions;
using LibUsbDotNet;
using LibUsbDotNet.Main;

namespace Examples
{
    internal class ReadWrite
    {
        public static UsbDevice MyUsbDevice;

        #region SET YOUR USB Vendor and Product ID!

        public static UsbDeviceFinder MyUsbFinder = new UsbDeviceFinder(1234, 1);

        #endregion

        public static void Main(string[] args)
        {
            ErrorCode ec = ErrorCode.None;

            try
            {
                // Find and open the usb device.
                MyUsbDevice = UsbDevice.OpenUsbDevice(MyUsbFinder);

                // If the device is open and ready
                if (MyUsbDevice == null) throw new Exception("Device Not Found.");

                // If this is a "whole" usb device (libusb-win32, linux libusb)
                // it will have an IUsbDevice interface. If not (WinUSB) the 
                // variable will be null indicating this is an interface of a 
                // device.
                IUsbDevice wholeUsbDevice = MyUsbDevice as IUsbDevice;
                if (!ReferenceEquals(wholeUsbDevice, null))
                {
                    // This is a "whole" USB device. Before it can be used, 
                    // the desired configuration and interface must be selected.

                    // Select config #1
                    wholeUsbDevice.SetConfiguration(1);

                    // Claim interface #0.
                    wholeUsbDevice.ClaimInterface(0);
                }

                // open read endpoint 1.
                UsbEndpointReader reader = MyUsbDevice.OpenEndpointReader(ReadEndpointID.Ep01);

                // open write endpoint 1.
                UsbEndpointWriter writer = MyUsbDevice.OpenEndpointWriter(WriteEndpointID.Ep01);

                // Remove the exepath/startup filename text from the begining of the CommandLine.
                string cmdLine = Regex.Replace(
                    Environment.CommandLine, "^\".+?\"^.*? |^.*? ", "", RegexOptions.Singleline);

                if (!String.IsNullOrEmpty(cmdLine))
                {
                    int bytesWritten;
                    ec = writer.Write(Encoding.Default.GetBytes(cmdLine), 2000, out bytesWritten);
                    if (ec != ErrorCode.None) throw new Exception(UsbDevice.LastErrorString);

                    byte[] readBuffer = new byte[1024];
                    while (ec == ErrorCode.None)
                    {
                        int bytesRead;

                        // If the device hasn't sent data in the last 100 milliseconds,
                        // a timeout error (ec = IoTimedOut) will occur. 
                        ec = reader.Read(readBuffer, 100, out bytesRead);

                        if (bytesRead == 0) throw new Exception("No more bytes!");

                        // Write that output to the console.
                        Console.Write(Encoding.Default.GetString(readBuffer, 0, bytesRead));
                    }

                    Console.WriteLine("\r\nDone!\r\n");
                }
                else
                    throw new Exception("Nothing to do.");
            }
            catch (Exception ex)
            {
                Console.WriteLine();
                Console.WriteLine((ec != ErrorCode.None ? ec + ":" : String.Empty) + ex.Message);
            }
            finally
            {
                if (MyUsbDevice != null) 
                {
                    if (MyUsbDevice.IsOpen)
                    {
                        // If this is a "whole" usb device (libusb-win32, linux libusb-1.0)
                        // it exposes an IUsbDevice interface. If not (WinUSB) the 
                        // 'wholeUsbDevice' variable will be null indicating this is 
                        // an interface of a device; it does not require or support 
                        // configuration and interface selection.
                        IUsbDevice wholeUsbDevice = MyUsbDevice as IUsbDevice;
                        if (!ReferenceEquals(wholeUsbDevice, null))
                        {
                            // Release interface #0.
                            wholeUsbDevice.ReleaseInterface(0);
                        }

                        MyUsbDevice.Close();
                    }
                    MyUsbDevice = null;

                    // Free usb resources
                    UsbDevice.Exit();

                }

                // Wait for user input..
                Console.ReadKey();
            }
        }
    }
}
Example
CopyVB.NET
Imports System
Imports System.Text
Imports System.Text.RegularExpressions
Imports LibUsbDotNet
Imports LibUsbDotNet.Main

Namespace Examples
    Friend Class ReadWrite
        Public Shared MyUsbDevice As UsbDevice

        #Region "SET YOUR USB Vendor and Product ID!"

        Public Shared MyUsbFinder As New UsbDeviceFinder(1234, 1)

        #End Region

        Public Shared Sub Main(args As String())
            Dim ec As ErrorCode = ErrorCode.None

            Try
                ' Find and open the usb device.
                MyUsbDevice = UsbDevice.OpenUsbDevice(MyUsbFinder)

                ' If the device is open and ready
                If MyUsbDevice Is Nothing Then
                    Throw New Exception("Device Not Found.")
                End If

                ' If this is a "whole" usb device (libusb-win32, linux libusb)
                ' it will have an IUsbDevice interface. If not (WinUSB) the 
                ' variable will be null indicating this is an interface of a 
                ' device.
                Dim wholeUsbDevice As IUsbDevice = TryCast(MyUsbDevice, IUsbDevice)
                If Not ReferenceEquals(wholeUsbDevice, Nothing) Then
                    ' This is a "whole" USB device. Before it can be used, 
                    ' the desired configuration and interface must be selected.


                    ' Select config #1
                    wholeUsbDevice.SetConfiguration(1)

                    ' Claim interface #0.
                    wholeUsbDevice.ClaimInterface(0)
                End If

                ' open read endpoint 1.
                Dim reader As UsbEndpointReader = MyUsbDevice.OpenEndpointReader(ReadEndpointID.Ep01)

                ' open write endpoint 1.
                Dim writer As UsbEndpointWriter = MyUsbDevice.OpenEndpointWriter(WriteEndpointID.Ep01)

                ' Remove the exepath/startup filename text from the begining of the CommandLine.
                Dim cmdLine As String = Regex.Replace(Environment.CommandLine, "^"".+?""^.*? |^.*? ", "", RegexOptions.Singleline)

                If Not [String].IsNullOrEmpty(cmdLine) Then
                    Dim bytesWritten As Integer
                    ec = writer.Write(Encoding.[Default].GetBytes(cmdLine), 2000, bytesWritten)
                    If ec <> ErrorCode.None Then
                        Throw New Exception(UsbDevice.LastErrorString)
                    End If

                    Dim readBuffer As Byte() = New Byte(1023) {}
                    While ec = ErrorCode.None
                        Dim bytesRead As Integer

                        ' If the device hasn't sent data in the last 100 milliseconds,
                        ' a timeout error (ec = IoTimedOut) will occur. 
                        ec = reader.Read(readBuffer, 100, bytesRead)

                        If bytesRead = 0 Then
                            Throw New Exception("No more bytes!")
                        End If

                        ' Write that output to the console.
                        Console.Write(Encoding.[Default].GetString(readBuffer, 0, bytesRead))
                    End While

                    Console.WriteLine(vbCr & vbLf & "Done!" & vbCr & vbLf)
                Else
                    Throw New Exception("Nothing to do.")
                End If
            Catch ex As Exception
                Console.WriteLine()
                Console.WriteLine((If(ec <> ErrorCode.None, ec & ":", [String].Empty)) & ex.Message)
            Finally
                If MyUsbDevice IsNot Nothing Then
                    If MyUsbDevice.IsOpen Then
                        ' If this is a "whole" usb device (libusb-win32, linux libusb-1.0)
                        ' it exposes an IUsbDevice interface. If not (WinUSB) the 
                        ' 'wholeUsbDevice' variable will be null indicating this is 
                        ' an interface of a device; it does not require or support 
                        ' configuration and interface selection.
                        Dim wholeUsbDevice As IUsbDevice = TryCast(MyUsbDevice, IUsbDevice)
                        If Not ReferenceEquals(wholeUsbDevice, Nothing) Then
                            ' Release interface #0.
                            wholeUsbDevice.ReleaseInterface(0)
                        End If

                        MyUsbDevice.Close()
                    End If
                    MyUsbDevice = Nothing

                    ' Free usb resources


                    UsbDevice.[Exit]()
                End If

                ' Wait for user input..
                Console.ReadKey()
            End Try
        End Sub
    End Class
End Namespace
Compiling the Code
  1. Create a new console application in your favorite designer.

  2. Verify your project references:

    • System.dll

    • LibUsbDotNet.dll

  3. Add/edit the main class. Copy/Paste code from one of the examples above.

Note: Example usb device firmware is located in the [InstallDirectory]\Benchmark\Firmware\[Manufacturer] directory.