为了与微控制器通信，我使用串行端口。我使用工作正常的 TCommPortDriver 2.1。但是，它缺乏检测新组件的添加或删除的能力。这在会话期间经常发生。
是否有一个事件可以告诉您何时添加或删除了组件？
更新 1
我尝试了 RRUZ 的第一个建议，并将其变成了一个独立的程序。它会在WM_DEVICECHANGE插入或拔出电缆时做出反应，但WParam不会显示设备的到达或移除。结果是：
msg = 537, wparam = 7, lparam = 0
msg = 537, wparam = 7, lparam = 0
msg = 537, wparam = 7, lparam = 0
拔出USB线时发送第一条消息，插入时发送第二条消息。消息部分显示WM_DEVICECHANGE消息（537）但WParam为7，不是WM_DEVICECHANGE或DBT_DEVICEARRIVAL。我对代码进行了一些修改，以便处理消息，但由于LParam为零，这没有用。结果与 VCL 和 FMX 相同。作为检查，请参见下面的代码。
更新 2
我现在运行了 WMI 代码。它仅在添加 COM 端口时触发，删除时没有反应。结果：
TargetInstance.ClassGuid : {4d36e978-e325-11ce-bfc1-08002be10318}
TargetInstance.Description : Arduino Mega ADK R3
TargetInstance.Name : Arduino Mega ADK R3 (COM4)
TargetInstance.PNPDeviceID : USB\VID_2341&PID_0044\64935343733351E0E1D1
TargetInstance.Status : OK
这是否可以解释在其他代码中这不被视为添加 COM 端口的事实？它似乎将新连接视为 USB 端口（实际上是什么）。Arduino 驱动程序将其转换为 COM 端口，但 WMI 无法识别。Windows 消息“看到”COM 端口更改，但无法检测到它是添加还是删除。
无论如何：设备更改有效。我只需要枚举 COM 端口即可查看实际存在的 COM 端口，这是我已经手动完成的。现在我可以用WM_DEVICECHANGE. 我只是向 CPDrv 组件添加一个事件。
感谢 RRUZ 的代码和帮助！
unit dev_change;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TProc = procedure (text: string) of object;
BroadcastHdr = ^DEV_BROADCAST_HDR;
DEV_BROADCAST_HDR = packed record
dbch_size: DWORD;
dbch_devicetype: DWORD;
dbch_reserved: DWORD;
end;
TDevBroadcastHdr = DEV_BROADCAST_HDR;
type
PDevBroadcastDeviceInterface = ^DEV_BROADCAST_DEVICEINTERFACE;
DEV_BROADCAST_DEVICEINTERFACE = record
dbcc_size: DWORD;
dbcc_devicetype: DWORD;
dbcc_reserved: DWORD;
dbcc_classguid: TGUID;
dbcc_name: Char;
end;
TDevBroadcastDeviceInterface = DEV_BROADCAST_DEVICEINTERFACE;
const
DBT_DEVICESOMETHING = $0007;
DBT_DEVICEARRIVAL = $8000;
DBT_DEVICEREMOVECOMPLETE = $8004;
DBT_DEVTYP_DEVICEINTERFACE = $00000005;
type
TDeviceNotifyProc = procedure(Sender: TObject; const DeviceName: String) of Object;
TDeviceNotifier = class
private
hRecipient: HWND;
FNotificationHandle: Pointer;
FDeviceArrival: TDeviceNotifyProc;
FDeviceRemoval: TDeviceNotifyProc;
FOnWin: TProc;
procedure WndProc(var Msg: TMessage);
public
constructor Create(GUID_DEVINTERFACE : TGUID);
property OnDeviceArrival: TDeviceNotifyProc read FDeviceArrival write FDeviceArrival;
property OnDeviceRemoval: TDeviceNotifyProc read FDeviceRemoval write FDeviceRemoval;
destructor Destroy; override;
property OnWin: TProc read FOnWin write FOnWin;
end;
TForm1 = class(TForm)
Memo: TMemo;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
{ Private declarations }
DeviceNotifier : TDeviceNotifier;
public
{ Public declarations }
procedure arrival(Sender: TObject; const DeviceName: String);
procedure report (text: string);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
constructor TDeviceNotifier.Create(GUID_DEVINTERFACE : TGUID);
var
NotificationFilter: TDevBroadcastDeviceInterface;
begin
inherited Create;
hRecipient := AllocateHWnd(WndProc);
ZeroMemory (@NotificationFilter, SizeOf(NotificationFilter));
NotificationFilter.dbcc_size := SizeOf(NotificationFilter);
NotificationFilter.dbcc_devicetype := DBT_DEVTYP_DEVICEINTERFACE;
NotificationFilter.dbcc_classguid := GUID_DEVINTERFACE;
//register the device class to monitor
FNotificationHandle := RegisterDeviceNotification(hRecipient, @NotificationFilter, DEVICE_NOTIFY_WINDOW_HANDLE);
end;
procedure TDeviceNotifier.WndProc(var Msg: TMessage);
var
Dbi: PDevBroadcastDeviceInterface;
begin
OnWin (Format ('msg = %d, wparam = %d, lparam = %d', [msg.Msg, msg.WParam, msg.LParam]));
with Msg do
if (Msg = WM_DEVICECHANGE) and ((WParam = DBT_DEVICEARRIVAL) or (WParam = DBT_DEVICEREMOVECOMPLETE) or
(WParam = DBT_DEVICESOMETHING)) then
try
Dbi := PDevBroadcastDeviceInterface (LParam);
if Dbi.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE then
begin
if WParam = DBT_DEVICEARRIVAL then
begin
if Assigned(FDeviceArrival) then
FDeviceArrival(Self, PChar(@Dbi.dbcc_name));
end
else
if WParam = DBT_DEVICEREMOVECOMPLETE then
begin
if Assigned(FDeviceRemoval) then
FDeviceRemoval(Self, PChar(@Dbi.dbcc_name));
end;
end;
except
Result := DefWindowProc(hRecipient, Msg, WParam, LParam);
end
else
Result := DefWindowProc(hRecipient, Msg, WParam, LParam);
end;
destructor TDeviceNotifier.Destroy;
begin
UnregisterDeviceNotification(FNotificationHandle);
DeallocateHWnd(hRecipient);
inherited;
end;
procedure TForm1.arrival(Sender: TObject; const DeviceName: String);
begin
report (DeviceName);
ShowMessage(DeviceName);
end;
procedure TForm1.FormCreate(Sender: TObject);
const
GUID_DEVINTERFACE_COMPORT : TGUID = '{86E0D1E0-8089-11D0-9CE4-08003E301F73}';
begin
DeviceNotifier:=TDeviceNotifier.Create(GUID_DEVINTERFACE_COMPORT);
DeviceNotifier.FDeviceArrival:=arrival;
DeviceNotifier.OnWin := report;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
DeviceNotifier.Free;
end;
procedure TForm1.report (text: string);
begin
Memo.Lines.Add (text);
end;
end.