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PAGE OPENTHERM
The Opentherm protocol was born with a very specific intention: to interface an "intelligent" thermostat with a boiler. By intelligent thermostat we mean a thermostat which, in addition to communicating the ON/OFF command to the boiler (for which a clean contact is sufficient), also communicates other information (temperature set point, operating times, DHW set point, etc.) and which can in turn receive information from the boiler (typically for diagnostics: water outlet temperature, error codes, etc.). The Opentherm protocol is therefore not strictly speaking a BUS, because it is designed to connect ONLY ONE MASTER DEVICE (role performed by the thermostat) to ONLY ONE SLAVE DEVICE (the boiler).
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