Сервер с одним последовательным портом

The Modbus gateway mentioned below refers to Modbus RTU to Modbus TCP and does not involve the processing of Modbus ASCII data frames. Modbus ASCII only supports transparent transmission.
Беспроводной модем LoRa

1. Simple protocol conversion
The most common and common Modbus gateway function, simple protocol conversion is the most efficient Modbus gateway mode for data processing, it only extracts key fields in the data, and then encodes the extracted data with another protocol (Modbus RTUModbus TCP) send.
2. Multi-host gateway
The multi-host gateway can only work in the TCP server mode and can process multiple Modbus TCP host requests at the same time. The serial server receives other host requests when one host request is not completed. At this time, the serial server will perform on the RS485 bus. Arbitration output (in layman's terms, it blocks subsequent instructions).
3. Storage Gateway
The first thing to understand is that the communication rate of the serial port is much lower than that of the network port. The host usually only processes a few registers when requesting the RTU device. The "storage gateway" is used in this working environment.
4. Take the initiative to report
Active reporting is a mode created by the TCP host that does not support the Modbus protocol and still wants to query the RTU device. In this mode, the gateway directly acts as the host to automatically initiate a request to the connected RTU device and send the RTU device The returned result is directly uploaded to the server. The server only needs to parse the returned data. Active reporting only supports client mode. Active reporting supports the return of data frames in two formats (Modbus RTU and Modbus TCP formats). In this mode, only Modbus data frames are supported and non-Modbus data frames are not processed.
Сервер с одним последовательным портом