s7-300与s7-200通过EM277通讯时，对于EM277而言，有时需设置偏移量，其他不需设置。如，Hex Parameter　Assignment不需要设置。
Assigning Hex Parameters：
Parameter data is specified in hex format in the "Assigning Hex Parameters" folder. Prerequisite for an adaptation of the values is that you are acquainted with the structure of the parameter telegram of the DP Slave (see also EN 50170 or IEC 61158).