084B8522
by Danfoss
Danfoss supplies the 084B8522 controller as part of its MCX Programmable Controllers series. The unit provides sequence logic for refrigeration and HVAC machinery, integrating sensor feedback with digital outputs to keep process variables within set limits. In an industrial automation panel it acts as a dedicated, embedded controller, removing the need for a full PLC when only temperature management and basic I/O are required. Its microprocessor executes the MCX firmware library that includes PID temperature, defrost timing, and alarm management routines.
Electrical characteristics support global installations. The device operates from a single-phase 230 V supply at 50/60 Hz, and its circuitry draws only 2 VA, so cabinet thermal load stays low. An internal transformer galvanically isolates logic power from the mains, protecting connected sensors. Three relay contacts provide the unit’s discrete actuation capability; these are exposed as 3 digital outputs for compressors, fans, or alarms. Sensor compatibility covers the thermistor type NTC-M2020, and the front display allows technicians to read temperatures and adjust setpoints without external tools.
For additional temperature feedback two analog channels accept platinum and positive-temperature-coefficient elements. Supported probe formats include PTC 1000 and Pt 1000, and the controller offers 2 temperature sensor inputs so suction and ambient values can be tracked independently. Control logic is sized for a single refrigeration circuit, therefore the board can manage 1 compressor and 1 evaporator without reconfiguration. Network integration is possible through optional expansion cards that add Modbus and Lon communication, enabling supervisory systems to overwrite setpoints while the local panel maintains direct access via the integrated display.
