为什么不能对USB端口读写数据

我用DS2.5 生成的USB驱动程序，在编译通过后，不能对endpoint2读写，我用仿真器跟踪单片机程序发现，对endpoint2读时，第一次发读命令时，单片机程序中endpoint2口有反映，但以后就没有反映了，但单片机程序复位后，又能反映一次。有发现对endpoint2写时，单片机程序中endpoint2口都有反映，但USB驱动程序监测到的是写不成功，别人提供的USB驱动程序，对endpoint2读写都是正常的。是不是从驱动开发网上下的DS2.5有使用上的问题，请高手指点！
谢谢！
以下读操作程序是有DS2.5自动生成的：
NTSTATUS ZboarduDevice::Read(KIrp I)
{
t << \"Entering ZboarduDevice::Read, \" << I << EOL;
// TODO: Check the incoming request.  Replace \"FALSE\" in the following
// line with a check that returns TRUE if the request is not valid.

    if (FALSE) // If (Request is invalid)
{
// Invalid parameter in the Read request
I.Information() = 0;
return I.PnpComplete(this, STATUS_INVALID_PARAMETER);
}
 
// Always ok to read 0 elements.
if (I.ReadSize() == 0)
{
I.Information() = 0;
return I.PnpComplete(this, STATUS_SUCCESS);
}
 
// Declare a memory object
KMemory Mem(I.Mdl());

    ULONG dwTotalSize = I.ReadSize(CURRENT);
ULONG dwMaxSize = m_Endpoint2IN.MaximumTransferSize();
// If the total requested read size is greater than the Maximum Transfer
// Size for the Pipe, request to read only the Maximum Transfer Size since
// the bus driver will fail an URB with a TransferBufferLength of greater
// than the Maximum Transfer Size.
if (dwTotalSize > dwMaxSize)
{
ASSERT(dwMaxSize);
dwTotalSize = dwMaxSize;
}

// Allocate a new context structure for Irp completion
USB_COMPLETION_INFO* pCompInfo = new (NonPagedPool) USB_COMPLETION_INFO;
if (pCompInfo == NULL)
{
I.Information() = 0;
return I.PnpComplete(this, STATUS_INSUFFICIENT_RESOURCES);
}

// TODO: Select the correct pipe to read from

// Create an URB to do actual Bulk read from the pipe

PURB pUrb = m_Endpoint2IN.BuildBulkTransfer(
    Mem,       // Where is data coming from?
dwTotalSize,   // How much data to read?
TRUE,         // direction (TRUE = IN)
NULL, // Link to next URB
TRUE // Allow a short transfer
);        

if (pUrb == NULL)
{
delete pCompInfo;
I.Information() = 0;
return I.PnpComplete(this, STATUS_INSUFFICIENT_RESOURCES);
}

// Initialize context structure
pCompInfo->m_pClass = this;
pCompInfo->m_pUrb = pUrb;

    // Submit the URB to our USB device
NTSTATUS status;
status = m_Endpoint2IN.SubmitUrb(I, pUrb, LinkTo(ReadComplete), pCompInfo, 0);
return status;
}

////////////////////////////////////////////////////////////////////////
//  ZboarduDevice::ReadComplete
//
// Routine Description:
// Completion Handler for IRP_MJ_READ
//
// Parameters:
// I - IRP just completed by USB
// pContext - Context structure containing pointer to Urb
//
// Parameters:
// NTSTATUS - STATUS_SUCCESS
//
// Comments:
// This routine is called when USBD completes the read request
//

NTSTATUS ZboarduDevice::ReadComplete(KIrp I, USB_COMPLETION_INFO* pContext)
{
// Normal completion routine code to propagate pending flag

if (I->PendingReturned)
{
I.MarkPending();
}

NTSTATUS status = I.Status();
PURB pUrb = pContext->m_pUrb;
ULONG nBytesRead = 0;

if ( NT_SUCCESS(status) )
{
nBytesRead = pUrb->UrbBulkOrInterruptTransfer.TransferBufferLength;
if (nBytesRead > 0)
t << \"Read() got \" << nBytesRead<< \" bytes from USB\\n\";
    }

// Deallocate Urb and context structure
delete pUrb;
delete pContext;

// set returned count
I.Information() = nBytesRead;

// Plug and Play accounting
DecrementOutstandingRequestCount();

// allow IRP completion processing
return STATUS_SUCCESS;
}

你用的是ZBoard板吗？如果是的话，你可以换成DS201编译就好了。
偶问过Ray Yang斑竹，他也遇到过这个问题！

谢谢！在DS2.01中确实是可以的，但ds2.5是高版本，在DS2.5中有没有解救的办法。再次谢谢！

偶也不知道在DS2.5中有没有解救办法！DS2.5和DS2.6偶都试了，不行！ :(

谢谢！我还有一事请教：KIrp I,NTSTATUS status 的内容怎样才能在WATCH窗口中看到，我用WATCH I 无法加入，始终是invalid expression.再次谢谢！