FM458和SIMATIC CPU（当然也包括416）之间的通讯有三种方式，下面是FM458文档中的描述：
a. 4 bytes can be received from the SIMATIC-CPU using a process interrupt;
b. 128 bytes can be sent and received via SIMATIC I/O accesses;
c. extremely large data quantities can be sent and received using data blocks/sets。

至于方式的好坏不能一概而论吧，要根据你具体的要求及数据量的大小来选择。