BufLen
[in] Length of the transfer buffer provided by the user in bytes.
pReadBuffer
[out] pointer on transfer buffer with the bytes / words / double words already read
pDatLen
[out] pointer to the length of the data delivered in the buffer in bytes.
这是prodave的数据块得去函数的最后三个参数，求解释这三个参数怎么用的，小弟刚学，求大神帮助。