The interface module 531X121PCRALG1 is connected to form the master of the system. CP342-5 is the master/slave interface module for connecting S7-300 and profibus-DP, and CP 343-1 is the interface module for connecting S7-300 and industrial Ethernet. In this control system, in addition to the master station mentioned above, the slave station is composed of 22 ET200S and 22 ET200eco, which are distributed on two profibus networks. profibus-DP interface that comes with the CPU constitutes the profibus Ⅰ line, and CP 342-5 interface module constitutes the profibus Ⅱ line.

There are two types of IM151-1 interface modules used on the 531X121PCRALG1 slave: the basic type and the standard type. The number of power management modules and I/O modules that can be connected to the basic type interface module ranges from 2 to 12, while that of the standard type interface module ranges from 2 to 63. Therefore, when there are more I/O modules in the slave station, it is appropriate to use the standard type of interface module. The interface module is equipped with a Profibus address setting dip switch.

531X121PCRALG1 slave selected 8DI and 16DI two kinds of templates, the template structure is compact, the power supply of the template adopts 7/8′ power cord, the communication of the template adopts M12 communication connector. The wiring is flexible and fast, easy to plug and unplug. The interface module has two rotary coding switches for profibus address assignment.