Showing results for 
Search instead for 
Did you mean: 

Calling a Function node in a DLL to give force-feedback effect to a joystick (using DirectInput)




I have been working for a couple of weeks on writing a DLL in Visual C++ Studio. My intention is to write an exported function in the DLL to initialize a Logitech Force3Dpro joystick, setup a force feedback effect and run it using DirectInput. I would like to control this force feedback effect (in particular, the intensity of the feedback) from Labview by calling the function in the DLL.


I followed the FFConst example in Microsoft SDK DirectInput Samples for making an .exe file to setup and run force feedback effects. I have been able to build the DLL successfully with an exported function that can be accessed from Labview by "Call a function node". I tested the function by running simple functions such as addition and multiplication of integers, andconfirmed the fact that the DLL was built correctly. I have also included the DirectInput code for initializing and running the force feedback effect. I am able to compile and build the DLL with no problems.


The Problem:

The only problem that I have at this point is with setting SetCooperativeLevel for the DirectInput8 joystick device. I have to provide a top-level window handle to SetCooperativeLevel so that I can give the function exclusive access to the joystick. Since I am not making a window and am building a DLL, I am not sure what handle I am supposed to provide it so that the joystick can respond. I am not sure if passing a handle to the Labview window would work because it is accessing the DLL's function? I tried passing LabView window handle to the function and read the X-axisposition off the joystick, but it read some junk (huge long integer) - which lead me to believe that the problem is something to do with initializing the joystick.


For all practical purposes, I am a complete novice at DirectInput programming and working with Visual C++. Although, I have programmed in C++previously. I am sorry for the long message, but I wanted to give a bit of background so that my aim is clear.


Any help, advice or direction with this problem be very much appreciated. Thank you for your time!



0 Kudos
Message 1 of 1