Reinhard, On 2 Sep 2007, at 09:42, Reinhard Scheck wrote:
Piers Kittel wrote:One flash from the meter represents 1/800th of a kW. I modified my y axis to show the correct value - multiply by 1250 to give watts1/800th of a kW is 1.25 WattsSo, the math to convert a counter tick to Watts is COUNTER/1.25 instead ofmultiplying
I think I made a mistake in explaining what the flashes mean. 800 flashes represents 1 kW, so if rrdtool records 800 flashes, it is actually 1kW, and to get 1kW from 800, I need to multiply by 1.25. Actually, I have to multiply by a further thousand to get rid of the "milli".
Please bear in mind, that rrdtool COUNTERS are always stored as a rate. So the "step" (updating interval for rrd file) comes into account. You did not show usthe rrd file definitions (rrdtool info will show them).
It's attached to this email as it's slightly lengthy. I'm recording data for a period of 1 day, 1 week, 1 month, 1 year and 5 years.
meter.info
Description: Binary data
rrdtool graph -w 800 -h 250 --vertical-label "Watts" /home/piers/ software/rrdtool/leccyday.png DEF:usage=/home/piers/software/rrdtool/ meter.rrd:meter:MAX CDEF:realusage=usage,1250,\* LINE1:realusage#0000FF VDEF:usagemax=usage,MAXIMUM GPRINT:usagemax:"Max\: %lfw" > /dev/null I tried inserting a snippet "CDEF:usagemax2=usagemax,1250,*" but I got "ERROR: rpn expressions without DEF or CDEF variables are not supported"Refer to the DEF=usage instead
That fixed it - thanks! Thanks so very much for your time - it is much appreciated! Regards - Piers
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