Working with USB devices in .NET

Question

Using .Net (C#), how can you work with USB devices?

How can you detect USB events (connections/disconnections) and how do you communicate with devices (read/write).

Is there a native .Net solution to do this?

Answer 1

I've tried using SharpUSBLib and it screwed up my computer (needed a system restore). Happened to a coworker on the same project too.

I've found an alternative in LibUSBDotNet: http://sourceforge.net/projects/libusbdotnet Havn't used it much yet but seems good and recently updated (unlike Sharp).

EDIT: As of mid-February 2017, LibUSBDotNet was updated about 2 weeks ago. Meanwhile SharpUSBLib has not been updated since 2004.

Answer 2

There is no native (e.g., System libraries) solution for this. That's the reason why SharpUSBLib exists as mentioned by moobaa.

If you wish to roll your own handler for USB devices, you can check out the SerialPort class of System.IO.Ports.

Answer 3

I used the following code to detect when USB devices were plugged and unplugged from my computer:

class USBControl : IDisposable
    {
        // used for monitoring plugging and unplugging of USB devices.
        private ManagementEventWatcher watcherAttach;
        private ManagementEventWatcher watcherRemove;

        public USBControl()
        {
            // Add USB plugged event watching
            watcherAttach = new ManagementEventWatcher();
            //var queryAttach = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 2");
            watcherAttach.EventArrived += new EventArrivedEventHandler(watcher_EventArrived);
            watcherAttach.Query = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 2");
            watcherAttach.Start();

            // Add USB unplugged event watching
            watcherRemove = new ManagementEventWatcher();
            //var queryRemove = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 3");
            watcherRemove.EventArrived += new EventArrivedEventHandler(watcher_EventRemoved);
            watcherRemove.Query = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 3");
            watcherRemove.Start();
        }

        /// <summary>
        /// Used to dispose of the USB device watchers when the USBControl class is disposed of.
        /// </summary>
        public void Dispose()
        {
            watcherAttach.Stop();
            watcherRemove.Stop();
            //Thread.Sleep(1000);
            watcherAttach.Dispose();
            watcherRemove.Dispose();
            //Thread.Sleep(1000);
        }

        void watcher_EventArrived(object sender, EventArrivedEventArgs e)
        {
            Debug.WriteLine("watcher_EventArrived");
        }

        void watcher_EventRemoved(object sender, EventArrivedEventArgs e)
        {
            Debug.WriteLine("watcher_EventRemoved");
        }

        ~USBControl()
        {
            this.Dispose();
        }


    }

You have to make sure you call the Dispose() method when closing your application. Otherwise, you will receive a COM object error at runtime when closing.

Answer 4

I'd recommend LibUSBDotNet, the library I have been using for 2 years. If you have to work with an USB device (send requests, process responses), this library was the best solution I could find.

Pros:

• Has all methods you need to work in synch or asynch mode.
• Source code provided
• Enough samples to start using it straight away.

Cons:

• Poor documentation (it's common problem for open source projects). Basically, you can find just common description of methods in the CHM help file and that's it. But I still find provided samples and source code is enough for coding. Just sometimes I see a strange behaviour and want to know why it was implemented in this way and can't get even a hint...
• Seems unsupported any more. Last version was issued in Oct 2010. And it's hard to get answers sometimes.