Creating A Virtual Channel Using Time Offset Arrays

[gillecaluimi]

I'm sampling a solar installation inverter where one of the channels is the cumulative kWh energy production.  This register is updated approx every 5 minutes by the inverter  and I'm trying to create a virtual channel to show the delta kW every five minutes produced but I't not generating an array.

I created a virtual channel with expression = (power[0]-power[4]) where the power[] table is created by sampling the inverter kWH channel every minute.....but this expression only generates a single value rather than creating a timed value array

[AzeoTech]

Do:

 

(power[0,100000] - power[4,100000])

 

Its not exactly right because of slight differences in dT.  Its better to create another channel and stuff the last result in that channel.