COM和VID/PID没有必然的联系。因为COM是串口设备，而VID/PID是USB设备所有的。
当USB设备插入后，有些驱动程序可以把USB
模拟为串口，而当虚拟串口被创建后，你本贴的代码收到DBT_DEVTYP_PORT通知，因此你得到了COM口信息。
DBT_DEVTYP_PORT不能让你直接得到USB的信息，你可以通过SetupDixxx系列的API来关联虚拟COM口和USB设备，然后得到USB的VID/PID，但是总的比较麻烦。
另一种‘比较’简单的方法是订阅USB设备通知。比如你可以订阅DBT_DEVTYP_DEVICEINTERFACE，并指定要求USB设备通知。但是，跟DBT_DEVTYP_PORT不一样的是，DBT_DEVTYP_DEVICEINTERFACE需要你显式地调用RegisterDeviceNotification。由于下例适用于各种USB设备，包括U盘，USB打印机等等，你可能需要用到达时间来关联USB设备和虚拟串口设备。
详细步骤见例子：
using System;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.Load += delegate { RegisterUsbDeviceNotification(); };
this.FormClosed += delegate { /* UnregisterDeviceNotification(cookie); */};
}
private void RegisterUsbDeviceNotification()
{
var filter = new DEV_BROADCAST_DEVICEINTERFACEW()
{
hdr = new DEV_BROADCAST_HDR()
{
dbch_Size = DEV_BROADCAST_DEVICEINTERFACEW.Size,
dbch_DeviceType = DBT_DEVTYP_DEVICEINTERFACE,
},
dbcc_classguid = GUID_DEVINTERFACE_USB_DEVICE
};
IntPtr cookie = RegisterDeviceNotification( // 1
this.Handle,
ref filter,
DEVICE_NOTIFY_WINDOW_HANDLE);
}
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_DEVICECHANGE)
{
switch (m.WParam.ToInt32())
{
case DBT_DEVICEARRIVAL:
var hdr = (DEV_BROADCAST_HDR)Marshal.PtrToStructure(m.LParam, typeof(DEV_BROADCAST_HDR));
if (hdr.dbch_DeviceType == DBT_DEVTYP_DEVICEINTERFACE)
{
IntPtr pName = m.LParam + DEV_BROADCAST_DEVICEINTERFACEW.Size - sizeof(char);
string name = Marshal.PtrToStringUni(pName); // 2
var match = Regex.Match(name, @"USB#VID_(?<vid>\w{4})&PID_(?<pid>\w{4})");
if (match.Success) \\ 3
{
this.Text = string.Format(
"vid={0} pid={1}",
match.Groups["vid"].Value,
match.Groups["pid"].Value
);
}
}
break;
case DBT_DEVICEREMOVECOMPLETE:
break;
}
}
base.WndProc(ref m);
}
const int WM_DEVICECHANGE = 0x219;
const int DBT_DEVICEARRIVAL = 0x00008000;
const int DBT_DEVICEREMOVECOMPLETE = 0x8004;
const int DBT_DEVTYP_DEVICEINTERFACE = 0x00000005;
const int DEVICE_NOTIFY_WINDOW_HANDLE = 0x00000000;
static Guid GUID_DEVINTERFACE_USB_DEVICE = new Guid("{A5DCBF10-6530-11D2-901F-00C04FB951ED}");
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
static extern IntPtr RegisterDeviceNotification(
IntPtr hRecipient,
ref DEV_BROADCAST_DEVICEINTERFACEW NotificationFilter,
uint Flags);
[StructLayout(LayoutKind.Sequential)]
struct DEV_BROADCAST_HDR
{
public int dbch_Size;
public int dbch_DeviceType;
public int dbch_Reserved;
}
[StructLayout(LayoutKind.Sequential)]
struct DEV_BROADCAST_DEVICEINTERFACEW
{
public DEV_BROADCAST_HDR hdr;
public Guid dbcc_classguid;
public char dbcc_name;
public static readonly int Size = Marshal.SizeOf(typeof(DEV_BROADCAST_DEVICEINTERFACEW));
}
}
}
注释1：订阅通知，订阅那些DeviceInterface为USB_DEVICE的通知。
注释2：得到设备路径，类似\?\USB#
VID_05AC&PID_1294&MI_00#0#{6bdd1fc6-810f-11d0-bec7-08002be2092f}。
注释3：VID和PID可以在USB的设备路径中得到。
资源：
关于RegisterDeviceNotification
https://msdn.microsoft.com/zh-cn/library/windows/desktop/aa363431.aspx
关于DEV_BROADCAST_DEVICEINTERFACE
https://msdn.microsoft.com/zh-cn/library/windows/desktop/aa363244.aspx
关于GUID_DEVINTERFACE_USB_DEVICE
https://msdn.microsoft.com/zh-cn/library/windows/hardware/ff545972.aspx
