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prodave6.2的数据块读取函数的最后三个参数，求这三个参数什么意思以及怎么用，泪求大神帮忙。
