Modbus RTU to MQTT Gateway

Modbus RTU to MQTT Gateway over 4G is an industrial IoT Gateway, widely used in Industrial IoT Applications. 
Lots of Meters, PLC, Sensors, devices, VFD supports Modbus RTU Protocol, and now, the user want to connect the deivces to Cloud Platform, in this application, will need the Modbus RTU to MQTT Gateway to convert Modbus RTU to MQTT protocols.
King Pigeon provides serval models for this applications, e.g: D221, S175, S375, S272, S275, S475, BL100, MxxxT, R40 for difference applications.