Question

Basically, I am trying to control a USB device (a linear actuator control board) using the supplied DLL (mpusbapi.dll) and header file (mpusbapi.h). However, I can’t for the life of me figure out which parameters I need to pass into MPUSBWrite().

In particular, the 2nd, 3rd and 4thparameters of MPUSBWrite(). The first parameter is clearly the handle that is returned by MPUSBOpen() and the last parameter is a timeout in ms.

I have a hunch it has something to do with page 6 of LAC advance config.

Any help is GREATLY appreciated. Thanks!

mpusbapi.h file

#ifndef _MPUSBAPI_H_
#define _MPUSBAPI_H_

#define MPUSB_FAIL                  0
#define MPUSB_SUCCESS               1

#define MP_WRITE                    0
#define MP_READ                     1

// MAX_NUM_MPUSB_DEV is an abstract limitation.
// It is very unlikely that a computer system will have more
// then 127 USB devices attached to it. (single or multiple USB hosts)
#define MAX_NUM_MPUSB_DEV           127

DWORD (*MPUSBGetDLLVersion)(void);

DWORD (*MPUSBGetDeviceCount)(PCHAR pVID_PID);

HANDLE (*MPUSBOpen)(DWORD instance,         // Input
             PCHAR pVID_PID,            // Input
             PCHAR pEP,                 // Input
             DWORD dwDir,               // Input
             DWORD dwReserved);         // Input <Future Use>

DWORD (*MPUSBRead)(HANDLE handle,           // Input
            PVOID pData,                // Output
            DWORD dwLen,                // Input
            PDWORD pLength,             // Output
            DWORD dwMilliseconds);      // Input

DWORD (*MPUSBWrite)(HANDLE handle,          // Input
             PVOID pData,               // Input
             DWORD dwLen,               // Input
             PDWORD pLength,            // Output
             DWORD dwMilliseconds);     // Input

DWORD (*MPUSBReadInt)(HANDLE handle,        // Input
               PVOID pData,             // Output
               DWORD dwLen,             // Input
               PDWORD pLength,          // Output
               DWORD dwMilliseconds);   // Input

BOOL (*MPUSBClose)(HANDLE handle);

#endif

LACTesting.cpp file

#include <windows.h>     // This is a windows header file. The functions I mentioned above are declared here
#include "mpusbapi.h"    // This is the header file supplied. It declares the function prototypes that are defined in the DLL
#include <iostream>
#include "ioctls.h"

using namespace std;

int main(int argc, char* argv)
{
// Try to load the library
HMODULE mpbusDLL = NULL;
mpbusDLL = LoadLibrary(L"mpusbapi.dll");

if (mpbusDLL != NULL) {
    // If the library could be loaded, then load the functions using GetProcAddress()

    // Load the function 'MPUSBOpen' from the DLL
    MPUSBOpen = (HANDLE(*)(DWORD, PCHAR, PCHAR, DWORD, DWORD)) GetProcAddress(mpbusDLL, "_MPUSBOpen");
    MPUSBOpen=(HANDLE(*)(DWORD,PCHAR,PCHAR,DWORD,DWORD))GetProcAddress(mpbusDLL,"_MPUSBOpen");
    MPUSBGetDLLVersion=(DWORD(*)(void))GetProcAddress(mpbusDLL,"_MPUSBGetDLLVersion");
    MPUSBGetDeviceCount=(DWORD(*)(PCHAR))GetProcAddress(mpbusDLL,"_MPUSBGetDeviceCount");
    MPUSBWrite=(DWORD(*)(HANDLE,PVOID,DWORD,PDWORD,DWORD))GetProcAddress(mpbusDLL,"_MPUSBWrite");
    MPUSBRead=(DWORD(*)(HANDLE,PVOID,DWORD,PDWORD,DWORD))GetProcAddress(mpbusDLL,"_MPUSBRead");
    MPUSBReadInt=(DWORD(*)(HANDLE,PVOID,DWORD,PDWORD,DWORD))GetProcAddress(mpbusDLL,"_MPUSBReadInt");
    MPUSBClose=(BOOL(*)(HANDLE))GetProcAddress(mpbusDLL,"_MPUSBClose");
}
//If the DLL didn't load, let me know!
else cout<<"DLL didn't load"<<endl;

//Declarations
HANDLE LACHandle;
PCHAR pipeName=MCHPUSB_PIPE_NAME;// intializes pipeName to "\\MCHP_EP"
PCHAR VidPid="vid_04d8&pid_fc5f";

LACHandle=MPUSBOpen(0,VidPid,pipeName,1,0);//open device connection
                //Not sure if I pass in the correct arguements for MBUSBOpen. VidPid and pipeName are correct.

cout<<"Device ID "<<VidPid<<"is open with "<<MPUSBGetDeviceCount(VidPid)<<" device(s)."<<endl;
//sMPUSBWrite(LACHandle,,3,,1000); <- this is where I am having issues.
                                    //I can't figure out how to use MPUSBWrite
MPUSBClose(LACHandle);// closes device connection

}

Answer 1

I think you should take a look at

Win32 Data Types

then work on Windows System Programming samples, then you will clearly understand the logic.

To your question, as i see the code i can guess

         // yourData which want to write
         PVOID pData
         // sizeof(yourData)  google "sizeof"
         DWORD dwLen
         /* I have no idea about this, but its output you can see it 
         after running function */               
         PDWORD pLength           

Hope this helps