Using time for subsetting

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Would appreciate your help again, in order for us to get averages of kWh produced I have been reading the same modbus register at once a second with muliple channels that have varying histroy times and then averaging the channels. I thought that if I read the same channel with a history of 24 hrs and then AVG time subsets of the channel it would create less overhead. Although the likes of

Avg((Feeder2_kW[SysTime()-1800, Systime()])+(Feeder1_kW[SysTime()-1800, Systime()]))

seems to work OK for a rolling AVG when I try

Avg((Feeder2_kW[8h 30m, 9h])+(Feeder1_kW[8h 30m, 9h]))

I still get an ever changing number whereas I expected a fixed result(unless we passed into a new 24 hr period). Can you tell me if 8h 30m is fixed or is it 8h 30m ago ?. I just wish to average different time slots within a twenty four hour period but some of these must relate to specific times ie: average power produced between 08.30 to 09.00. I am probably makeing this far too complicated as usual and would appreciate your advice.


Steve Lawrence

Stewart Island NZ

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8h30 and 9h are all absolute time. 8:30 and 9:00 this morning. At midnight, they change to the next day and thus become in the future for 8.5 and 9 hours respectively.

The problem is most likely that you put a space between 8h and 30m. The time value can't have spaces in it.

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