Monitoring status of COM port (connected or disconnected)

[vlkc]

Hello,

Does anybody know how to monitor COM? Here is the sample:

{ 
  Some applications need to know when the user inserts or 
  removes a compact disc or DVD from a CD-ROM drive without 
  polling for media changes. Windows provide a way to notify these 
  applications through the WM_DEVICECHANGE message. 
}

 type
   TForm1 = class(TForm)
   private
     procedure WMDeviceChange(var Msg: TMessage); message WM_DEVICECHANGE;
   public

   end;

 {...}

 implementation

 {$R *.DFM}

 procedure TForm1.WMDeviceChange(var Msg: TMessage);
 const
   DBT_DEVICEARRIVAL = $8000; // system detected a new device 
  DBT_DEVICEREMOVECOMPLETE = $8004;  // device is gone 
var
   myMsg: string;
 begin
   inherited;
   case Msg.wParam of
     DBT_DEVICEARRIVAL: myMsg  := 'CD inserted!';
     DBT_DEVICEREMOVECOMPLETE: myMsg := 'CD removed!';
   end;
   ShowMessage(myMsg);
 end;

 

How to realize it in UniGui ServerModule?

 

{ 
  Some applications need to know when the user inserts or 
  removes a compact disc or DVD from a CD-ROM drive without 
  polling for media changes. Windows provide a way to notify these 
  applications through the WM_DEVICECHANGE message. 
}

 type
   TUniServerModule = class(TUniGUIServerModule)
   private
     procedure WMDeviceChange(var Msg: TMessage); message WM_DEVICECHANGE;
   public

   end;

 {...}

 implementation

 {$R *.DFM}

 procedure TUniServerModule.WMDeviceChange(var Msg: TMessage);
 const
   DBT_DEVICEARRIVAL = $8000; // system detected a new device 
  DBT_DEVICEREMOVECOMPLETE = $8004;  // device is gone 
var
   myMsg: string;
 begin
   inherited;
   case Msg.wParam of
     DBT_DEVICEARRIVAL: myMsg  := 'CD inserted!';
     DBT_DEVICEREMOVECOMPLETE: myMsg := 'CD removed!';
   end;
   ShowMessage(myMsg);
 end;

I this way does not work Please help.

[alfr]

Not sure I understood the use of CD in combination with unigui. But you can’t push data from the server to the various client sessions, instead the clients needs to pull the data/info from the server. 

[Abaksoft]

@vlkc,

From your title request, for monitoring COM port, you have an excellent library

http://nrcommlib.com/nrcomm/index.html

it contains a huge of components. Some of them work fine with unigui (as they are not GUI). That said, this will work only in server side !