General USB driver(VC winXP) can't read/write msg with S7 USB Adapter?

[chenhg]

Hallo all:
Recently we have released our MPI driver using S7 Serial adapter(without Prodave comm lib).Now we want to write MPI OPC driver using S7 USB adapter.but when we call function Readfile(),the PC restart.The following is partion of the source code about usb communication.Appreciate anyone help me.

//find usb adapter (success)
if(sDevice.Find("vid_0908")!=-1 && sDevice.Find("pid_0004")!=-1)
{
hHid = CreateFile ( strtDetailData->DevicePath,
GENERIC_READ | GENERIC_WRITE,
NULL/*FILE_SHARE_READ |FILE_SHARE_WRITE*/,
NULL,
2,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED |
FILE_FLAG_WRITE_THROUGH,
0);
}

//Write msg(Get return code :997)
DWORD length;
DWORD nSendByte = 1;
BYTE buff1[256];
buff1[0] = 2;
//if(!WriteFile(hHid,buff1,nSendByte,&length,&_wo))
if(!WriteFile(hHid,buff1,nSendByte,&length,NULL))
{
DWORD d = GetLastError();
if(d != ERROR_IO_PENDING)
length = 0;
}
//Readfile(PC Restart)
ReadFile(hHid,buff,nReadByte,&length,&_ro)

 

[rdrast]

What are your declarations?
It looks like you at least are using uninitialized nReadByte and length.

Why are you opening the file, with mode OVERLAPPED, writing to it without reference to an OVERLAPPED structure, then trying to read it using an OVERLAPPED structure? You have to do one, or the other. OVERLAPPED or not. The same (properly initialized) OVERLAPPED should be passed to all calls (read/write/etc) operating against that handle.

Additionally, you should not be using _wo and _ro as names. Leading underscores are reserved for the compiler, and shouldn't be used by users.