如何从USB rfid阅读器读取? [英] How to read from a usb rfid reader?

问题描述

我买了一个 USB rfid 阅读器.用户在设备前放置 rfid 标签时如何读取数据?

I have bought a usb rfid reader. How can I read data when user puts an rfid tag in front of the device?

我的计算机将该设备识别为人机接口设备.如果它将其识别为 com 设备，则从带有 serialPort 对象的设备读取要容易得多，但我不知道如何从 USB 设备读取.

my computer identifies the device as an Human Interface Device. If it identified it as an com device it was much easier to read from the device with serialPort object but I dont know how to read from a usb device.

有什么帮助吗?

推荐答案

当我遇到同样的问题时，我就是这样做的.

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();
        }
    }
  }
}

按供应商和产品 ID 打开 USB 设备.

Opens a USB device by vendor and product id.

打开一个用于阅读的 UsbEndpointReader 类.

Opens a UsbEndpointReader class for reading.

读取并显示来自 Ep01 的 USB 设备输出，直到 5 秒内没有接收到数据.

Reads and displays usb device output from Ep01 until no data is received for 5 seconds.

这篇关于如何从USB rfid阅读器读取?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！