Adding an interface for the ShackLan-4 system into a logging program is a simple process using Windows messages. This method is preferred as it requires no DLL files and generates no errors if files are not found. Simply add a few variables and a message handler to build the remote control interface. Step by step instructions are listed below. Sample code is in Delphi Pascal but is easily adapted to other languages. We assume you are fluent in the language of your choice and cannot help you implement the interface into your software.

Message definitions (in hex):

• 01h - Get Shacklan-4 application handle

• 02h - Shacklan-4 handle

• 03h - Switch focus to logger

• 04h - Test connection

• 05h - Connection good

• 11h - Radio 1 band

• 12h - Radio 2 band

Declarations

 First declare variables for the application handle of the ShackLan-4 software, Shacklan-4 message, connection timer and bands for each radio. Next add constants for the messages and connection timeout timer.

var
   ShacklanHandle:    THandle;
   ShacklanMsg:        cardinal;
   ShacklanTimer:      integer;
   Radio1Band,
   Radio2Band:           integer;

const
  msgGetShacklanHandle = $01;
  msgShacklanHandle    = $02;
  msgBringToFront      = $03;
  msgTestConnection    = $04;
  msgConnectionGood    = $05;

  msgRadio1Band        = $11;
  msgRadio2Band        = $12;
  ShacklanTimeout      = 5;

Logger Startup

   When your program is started it should first register a "shacklan4" message with the operating system. Next reset the handle for the Shacklan-4 application and the connection timer. The last step in starting is to send a broadcast message to locate the Shacklan-4 application. If it is running it send a message containing the application handle which is used in all other messages.

 Sample code:

ShacklanMsg := RegisterWindowMessage ('shacklan4');
ShacklanHandle := 0;
ShacklanTimer := 0;
SendMessage (HWND_BROADCAST, ShacklanMsg,  msgShacklanHandle, 0);
 

Handling messages

   There are 3 messages sent from the Shacklan-4 application to your logger that you need to handle.

procedure TMsgDemo.AppMessage (var Msg: TMsg; var Handled: Boolean);

begin
if (Msg.Hwnd = Application.Handle) then   // Is message for your logger?
   begin
   if Msg.Message = ShacklanMsg then  // Is message from Shacklan-4 application?
      begin
      case Msg.wParam of  // Message type is in WParam, data is in LParam

         msgShacklanHandle:  // Message containing handle of Shacklan-4 application
            begin
            ShacklanHandle := Msg.LParam;  // Set handle for further messages to Shacklan-4 application
            Handled := true;
            ShacklanTimer := ShacklanTimeout;  // Reset link timeout timer
            end;

         msgConnectionGood: // Message from Shacklan-4 application indicating good link
            begin
            Handled := true;
            ShacklanTimer := ShacklanTimeout; // Reset link timeout timer
            end;

         msgBringToFront:  // Message to set user focus to logger
            begin
            SetForegroundWindow (Application.MainForm.Handle);
            Handled := true;
            end;
         end;
      end;
   end;
   inherited;
end;

Sending band information

 Band information is sent in numerical format indicating the band according to the following table:

PostMessage (ShacklanHandle, ShacklanMsg, msgRadio1Band, Radio1Band);
PostMessage (ShacklanHandle, ShacklanMsg, msgRadio2Band, Radio2Band);
 

Maintaining a robust connection

   It is important that you have a system in place to maintain the connection even if the Shacklan-4 application is closed and restarted. This is the purpose of the timeout timer. The following sample code executes once every second.

procedure TMsgDemo.Timer1Timer (Sender: TObject);

begin
if ShacklanHandle <> 0 then  // If connection has been established
   PostMessage (ShacklanHandle, ShacklanMsg, msgConnection, GetForegroundWindow)
else  // If no connection
   PostMessage (HWND_BROADCAST, ShacklanMsg, msgLoggerHandle, Application.Handle);

if ShacklanTimer > 0 then  // Decrement timeout timer.
   dec (ShackLanTimer)
else
   ShacklanHandle := 0;  // Reset Shacklan-4 application handle if no response for timeout period

//Send the band information every second

PostMessage (ShacklanHandle, ShacklanMsg, msgRadio1Band, Radio1Band);
PostMessage (ShacklanHandle, ShacklanMsg, msgRadio2Band, Radio2Band);
end;