ConstReadonlyattributes: { ReadonlycumulativeIndicates the most recent measurement of cumulative energy exported by the server over the lifetime of the device, and the timestamp of when the measurement was recorded.
The reporting interval of this attribute shall be manufacturer dependent. The server may choose to omit publication of deltas considered not meaningful.
The server shall NOT mark this attribute ready for report if the last time this was done was more recently than 1 second ago.
The server may delay marking this attribute ready for report for longer periods if needed, however the server shall NOT delay marking this attribute as ready for report for longer than 60 seconds.
If the cumulative energy exported cannot currently be determined, a value of null shall be returned.
A ElectricalEnergyMeasurementCluster supports these elements if it supports features ExportedEnergy and CumulativeEnergy.