Hi Stefan, Without looking into it deeper, it sounds like you are trying to sum up all different Power-readings (W) to get a Energy reading (Wh).
If you do readings every 60 seconds, - you will end up with 1440 values during 24 hours. Lets say that you constant usage of 1000W. Then all readings for the whole 24 hours would be just 1000-readings. This should result in that you used 24000Wh - or 24kWh - as you used 1kWh for 24 hours. So you can't just summarize all your 1000W*1440values together, but you also needs to divide them by 60 - as you have 60 readings per hour - which is the new unit - I'm suppose you are looking for. I would go with a AVG RRD when creating it to get a average of the values collected when doing consolidations. Using the max will result in higher readings than what you actually have, as a very short high peak during reading can offset the values quite a lot. Hope that this give you some insight - and answered part of the question. /Johan On Wed, 2013-07-03 at 23:51 -0700, stefan wrote: > Hi, > I am struggling on a problem calculating the sum of a DS for the given > period. > I have a rrd: > rrdtool create PV.rrd --start now --step 10 DS:PVWatt:GAUGE:60:U:U > RRA:MAX:0.5:1:60480 > > the PVWatt has values from 0 to 5000 > > I want to Print to total amount of PVWatt for the given time period (24h) > My Graph looks like this: > c:/Programme/rrdtool/rrdtool.exe graph c:/wwwpics/PV.png --start noon-12h > --end noon+12h ^ > --title Photovoltaikanlage --width=600 --height=300 --alt-y-grid ^ > --upper-limit 5000 --lower-limit 0 --rigid ^ > DEF:Watt=PV.rrd:PVWatt:MAX LINE1:Watt#00FF00:Watt_cur ^ > VDEF:Wmin=Watt,MINIMUM ^ > VDEF:Wmax=Watt,MAXIMUM ^ > VDEF:Wavg=Watt,AVERAGE ^ > CDEF:Wmod=Watt,POP,Wmax,Wmin,- ^ > VDEF:Wtt=Wmod,LAST ^ > VDEF:Wlast=Wmod,LAST ^ > VDEF:first=Watt,FIRST ^ > COMMENT:" \l" ^ > COMMENT:"MAX Leistung \:" GPRINT:Wmax:"%%6.1lf Wp" ^ > COMMENT:" \l" ^ > COMMENT:"Start \:" GPRINT:first:"%%6.1lf Wp" > GPRINT:first:"%%c":strftime ^ > COMMENT:" \l" ^ > COMMENT:"Total Leistung\:" GPRINT:Wtt:"%%6.1lf Wh" > GPRINT:Wlast:"%%c":strftime ^ > COMMENT:" \l" > > > I have tried several calculations for Wmod/Wtt but all results are wrong. > I don't know how RRD is calculating the sum of PVWatt? > can someone light me up? > > Thanks > Stefan > > > > > -- > View this message in context: > http://rrd-mailinglists.937164.n2.nabble.com/how-to-calculate-the-sum-of-a-DS-tp7581099.html > Sent from the RRDtool Users Mailinglist mailing list archive at Nabble.com. > > _______________________________________________ > rrd-users mailing list > [email protected] > https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
_______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
