Converting to and from NMEA0183 XDR records =========================================== Basics ------ NMEA2000 has a much broader set of messages dealing with various sensor data then NMEA0183 has. In NMEA0183 there is (beside a small amount of predefined sentences) a more or less generic [XDR sentence](https://gpsd.gitlab.io/gpsd/NMEA.html#_xdr_transducer_measurement). As there is no out of the box complete mapping between NMEA2000 and NMEA0183 XDR possible you need to configure the mappings between NMEA2000 and XDR and vice versa. Mapping Parameters ------------------ Typically a NMEA2000 PGN that the gateway can map to an XDR record will belong to a certain category (like Temperature, Pressure, Engine,...), will potentially inlcude a source identifier (like SeaTemperature or OutsideTemperature), an instance id (0...255) and potentially a couple of fields (like EngineOilPressure, EngineCoolantTemp). You now need to select which combination of those values should be mapped to a particular XDR transducer name.  Simple Set Up ------------- To make the configuration easy the gateway will record information about NMEA2000 PGNs it could in principle map to XDR records - but without a current configuration. Just click "Show Unmapped" to get a list of those entities.  By clicking the "+" button beside the entry you will get a prefilled mapping. You just need to add the transducer name and save the settings. Instance Id handling -------------------- For the instance Id of a NMEA2000 message there are 3 options on how they can be used to convert to a transducer name: * single<br> exactly only this instance id is mapped to the selected transducer name. This should work for most receivers of the XDR records but requires a separate mapping for each of your instances. * auto<br> In this mode the instance will be added to the transducer name in the form of Temperature#001 - 001 being the instance id. This is recommended in NMEA0183 4.x - but not necessarily received by all devices. * ignore<br> All instances will map to the same transducer name. Backward Mapping ---------------- The configured mappings can work in both directions. So when an XDR record with a known transducer name, type and unit is received it is converted into a NMEA2000 PGN. You need to have the direction for the mapping set to "bidir" (the default). Export and Import ----------------- The mappings can be exported and imported as a json file from the UI. Handled PGNs ------------ The following PGNS are handled: | Category | from NMEA2000 | to NMEA2000 | |----------|---------------|-------------| | Fluid | 127505 | 127505 | | Battery | 127508 | 127508 | | Temperature | 130310, 130311, 130312, 130316 | 130312 | | Pressure | 130310, 130311, 130314 | 130314 | | Humidity | 130311, 130313 | 130313 | | Engine | 127489, 127488 | 127489, 127488 | Rate ---- To avoid resending the same XDR transducer to often you can set a minimum delay between sending it again (config/converter/min XDR interval, default 100ms).