The Open Protocol Gateway SMG-ESR is a flexible configuration data protocol converter for MQTT cloud users on the IOT. It mainly supports the conversion of Modbus-RTU device data to JSON format and transmitted through the MQTT protocol in Ethernet mode. The gateway's built-in web system supports configurating the gateway network parameters, cloud MQTT parameters, etc., And able to upload, check, and delete of device communication model files, device management files, and device rule files through the local web system. Data collection, cloud reporting, and remote control can be achieved through MQTT. The gateway complies with TH35-7.5 rail.