DA 3.0和2.0的区别是3.0增加了如下的接口(定义在opca.idl中),其余都一样
interface IOPCAsyncIO3: IOPCAsyncIO2
{
HRESULT ReadMaxAge(
[in] DWORD dwCount,
[in, size_is(dwCount)] OPCHANDLE* phServer,
[in, size_is(dwCount)] DWORD* pdwMaxAge,
[in] DWORD dwTransactionID,
[out] DWORD* pdwCancelID,
[out, size_is(,dwCount)] HRESULT** ppErrors
);
HRESULT WriteVQT(
[in] DWORD dwCount,
[in, size_is(dwCount)] OPCHANDLE* phServer,
[in, size_is(dwCount)] OPCITEMVQT* pItemVQT,
[in] DWORD dwTransactionID,
[out] DWORD* pdwCancelID,
[out, size_is(,dwCount)] HRESULT** ppErrors
);
HRESULT RefreshMaxAge(
[in] DWORD dwMaxAge,
[in] DWORD dwTransactionID,
[out] DWORD* pdwCancelID
);
}