This document describes the SEM88 sensor made by Initra d.o.o. It uses an LPC812 microcontroller to communicate with various sensors via I2C and transmit data via RS485. The sensors can measure air flow, door status, fan status, humidity, light, liquid levels, pressure, switch states, temperature, and vibration. Status is indicated by 6 LEDs and the temperature, humidity, and air flow sensor can measure within +/- 2% RH, +/- 0.5 °C, and provide a relative value from 0 to 100, respectively.