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Hi Stefan,<BR>
<BR>
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).<BR>
<BR>
If you do readings every 60 seconds, - you will end up with 1440 values during 24 hours.<BR>
<BR>
Lets say that you constant usage of 1000W. Then all readings for the whole 24 hours would be just 1000-readings.<BR>
This should result in that you used 24000Wh - or 24kWh - as you used 1kWh for 24 hours.<BR>
<BR>
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.<BR>
<BR>
I would go with a AVG RRD when creating it to get a average of the values collected when doing consolidations.<BR>
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.<BR>
<BR>
Hope that this give you some insight - and answered part of the question.<BR>
<BR>
/Johan<BR>
<BR>
On Wed, 2013-07-03 at 23:51 -0700, stefan wrote:
<BLOCKQUOTE TYPE=CITE>
<PRE>
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
--
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</PRE>
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