Sending instructions to USB device - api

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