I know how to calculate the kWh delta (the energy spent during the period) using Meta Data point. What I am not sure about is how to calculate the total kWh usage, I mean accumulating reading through time periods. What I am not sure about is how to get the last current kWh state and add the kWdelta to it and save it as a new value.
Let's assume I have values in the W.
// getting the current and the previous readings (W + time) var lastW = p.lastValue(1); var nowW = p.lastValue(0); // getting epoche period in milliseconds var period = nowW.time - lastW.time; //getting period in seconds periodS = period/1000 // getting the W readings var Wnow = nowW.value; var Wlast = lastW.value; // calculating the W delta Wdelta = Wnow - Wlast; // getting periods W seconds Wsdelta = Wdelta*periodS // getting Whdelta Whdelta = (1/3600)*Wsdelta //getting kWhdelta kWhdelta=(1/1000)*Whdelta // so how I can get the last point kWh value //assuming that the metadata point variable name is "my", should I return something like my.value + kWhdelta for the new value? return my.value+kWhdelta;