// Constructor
constructor TDaqThread.Create(OnTerminate:TNotifyEvent);
begin
  inherited Create(true);
  Self.OnTerminate:=OnTerminate;        // Defines the onTerminate event handler
  FreeOnTerminate:=true;                // Thread frees itself when it terminates
  Resume;                               // Start the thread
end;
 
// The thread executes a single procedure
procedure TDaqThread.Execute;
begin
  try
    MainForm.DoUpdateDaq;
  except
    on E:Exception do
    begin
     // Handle the error.
    end
  end;
end;
 
// Here is how I create/start the thread.  When it is done I run the 
// EndUpdateDaq procedure.
 
        DaqThread:=TDaqThread.Create(EndUpdateDaq)
 
// At the beginning of the EndUpdateDaq procedure...
procedure TMainForm.EndUpdateDaq(Sender:TObject);
begin
  try
    // Has the Daq thread been terminated?
    if DaqThread<>nil then
     if DaqThread.Terminated then
       Exit;
 
// More stuff...
 
end;
 
Procedure TMainForm.OnDestroy(Sender:TObject);
begin
  MonitorTimer.Enabled:=false;
 
  if DaqThread <> nil then
    if not DaqThread.Terminated then
    begin
      DaqThread.OnTerminate:=nil;
      DaqThread.Terminate;       // Stop the Daq thread
  //    DaqThread.WaitFor;         // Wait for it to terminate
    end;
 
// more stuff...
end;