How does Siemens s7-300 communicate with Johnson DX-9 100 485?

Modbus communication, right? Siemens s7-300 needs cp34 1 communication module. If et200s module can be used, the price of et200s communication module should be better. If multiple devices need to communicate, it is recommended to use the communication gateway of Germany and Youxun, which is convenient for configuration and does not need to consider fault handling and rotation training. Only simple settings are needed to achieve communication. Cp340 is used for ascii communication.