IoT-Based Temperature and Relative Humidity Monitoring System Using Simple Network Management Protocol

This paper proposes a system architecture design for the Internet of Things (IoT) implemented in temperature and relative humidity measurement using DHT 11 temperature and humidity sensor. Simple Network Management Protocol (SNMP) is used to manage different network devices and transfer information so that the ESP32 Wi-Fi microcontroller connected to the sensor can communicate with Open Platform Communication (OPC) server. In addition, the network variables are identified by Object Identifiers (OIDs) then collected to Management Information Base (MIB). These two elements are required by the SNMP monitoring tool for enabling the user to monitor network infrastructure and run troubleshooting. Data acquired from the ESP32 Wi-Fi microcontroller are accumulated on the OPC server using SNMP and subsequently transferred to the OPC Client such as Human Machine Interface (HMI) and OPC data logger. The OPC server has a ping channel feature to determine network latency measured as a round trip time – the time taken for data to get its destination and back again. Later on, the ESP32 microcontroller was also connected to a mobile application via Wi-Fi for displaying real-time data simultaneously with the HMI. The SNMP network latency test on the proposed system architecture design results in 126,33 ms for 13 minutes without a corrupt packet of data. The result indicates SNMP can be used as an alternative protocol for IoT data communication.