I have bought a usb rfid reader. How can I read data when user puts an rfid tag in front of the device?
my computer identifies the device as an Human Interface Devic
If they have given you a SDK with your reader then use it. otherwise you will have to know the hex commands of your reader.Send commands to reader and get response
This is what I did when I had the same problem.
using System;
using System.Text;
using LibUsbDotNet;
using LibUsbDotNet.Main;
namespace Examples
{
internal class ReadPolling
{
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-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))
{
// 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);
byte[] readBuffer = new byte[1024];
while (ec == ErrorCode.None)
{
int bytesRead;
// If the device hasn't sent data in the last 5 seconds,
// a timeout error (ec = IoTimedOut) will occur.
ec = reader.Read(readBuffer, 5000, out bytesRead);
if (bytesRead == 0) throw new Exception(string.Format("{0}:No more bytes!", ec));
Console.WriteLine("{0} bytes read", bytesRead);
// Write that output to the console.
Console.Write(Encoding.Default.GetString(readBuffer, 0, bytesRead));
}
Console.WriteLine("\r\nDone!\r\n");
}
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();
}
}
}
}
Opens a USB device by vendor and product id.
Opens a UsbEndpointReader class for reading.
Reads and displays usb device output from Ep01 until no data is received for 5 seconds.
Please see: How do I read input from a USB HID device?
The device might enumerate as generic HID but might behave like a keyboard. If so, it should just type out the characters it reads. If not, you'll have to poll it from the driver. That link should help.