Honeywell HPM Series Particle Sensor with UART Output Honeywell HPM Series Particle Sensor with UART (Universal Asynchronous Receiver/Transmitter) Output allows the user to more accurately and cost-effectively monitor or control environmental particulate contaminates. Industry-leading long life of 20,000 hours provides stable operation and continuous use. Honeywell HPM Series Particle Sensor outputs at PM2.5 utilizing a laser-based light scattering particle sensing method to detect and count particles in the concentration range of 0μg/m3 in a given environment. This fully calibrated sensor provides proven electromagnetic compatibility (EMC) performance, based on IEC61000. HPM features a response time of less than six seconds.