The Honeywell 301EM-20 Sensor Controller is designed for mechanical room gas detection systems, supporting up to 20 remote sensors. It is configurable to meet ASHRAE 15, B-52, and international mechanical code requirements. The controller offers flexible integration with a full range of sensors for toxic, combustible, and oxygen gases, as well as refrigerant detection.

Key features include an easy-to-read LCD display, auto-diagnostics, and multiple outputs: three 24 Vdc alarm outputs, four 4-20 mA outputs, and RS-485 Modbus communication. Four fully programmable relays allow for automatic fan, horn, and strobe activation, while manual override functions (latching relay, silence key) ensure operator control. The unit is built for reliable operation in mechanical room environments, with robust enclosure and straightforward installation.