The PN/PN coupler links two Ethernet subnets with one another and exchanges data. The maximum size of the data that can be transferred is 16-byte input data and 16-byte output data. In order to expand the address width of the PN/PN coupler from 16 bytes 112 bytes, an additional SDB needs to be installed on the controlle.

标准还是16个字节吧，想要增加到112字节，要安装相应的SDB的。