Hi Oliver, On 17.04.2013, at 14:25, Oliver Loch <grime...@gmx.net> wrote:
> Hi, > >> >> One 'tick' of your device is equal to 3600 Joules, which you consumed during >> the time between the previous tick and the current tick. >> That is why you use ABSOLUTE, see the documentation on what this does. >> >> For example, you get one tick after 10 seconds. That means you used 3600 >> joules in 10 seconds (which is an average of 360W during 10 seconds). When >> you update your database, RRDtool computes a rate of 360 and works with that >> during the normalization and consolidation phases. >> >> See my site ( http://rrdtool.vandenbogaerdt.nl/ ) for some information. > > Thanks a lot for pointing me into the right direction. I read the part about > "Rates, normalizing and consolidating" and it all became clear :) > >> Your step size is important when considering how much detail you want/need. >> You could set it to 1. > > I've set it to one and every time I get a signal I write 3600 to the > database. and the average power is shown just fine. > > One problem I hit now is that there can be more than 3600 ticks per hour. > Calculating the VA by the breakers and the usual current I end up with 3840 > (240V*16A) and 7680VA (240V*32A). I highly doubt that the power consumption > will ever hit the peak level, but levels above 3600 are possible. How should > I store that information into the database? Steps smaller than one second > aren't possible. they are, just provide a higher accuracy timestamp together with your update and all will be well. Note that N: is high precision by default, so if you are updating the rrd file in real time, just use N as your timestamp cheers tobi > Should I double the value that is written to the database? E.g. with two > signals per second 7200 instead of 3600 or is there a way to represent > multiple entries per second? > > Thinking about the unix timestamp I wonder if rrdtool then calculates the > average of multiple values per second and just stores that average to the db? > >> Your heartbeat value should be large enough to not miss updates that happen >> to be far apart. If all consumers in the house are off, almost no power is >> used. Your measuring device itself is the only one. Compute how long it >> takes for it to consume one Wh, double that time just to be sure, and set >> that as your heartbeat value. > > I set the heartbeat to 14000, as the device uses 0.5w/hour which gives me > 7200 seconds between ticks. > > Thanks! > > KR, > > Oliver > _______________________________________________ > rrd-users mailing list > rrd-users@lists.oetiker.ch > https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
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