<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi,<br><br><blockquote type="cite"><br>One 'tick' of your device is equal to 3600 Joules, which you consumed during <br>the time between the previous tick and the current tick.<br>That is why you use ABSOLUTE, see the documentation on what this does.<br><br>For example, you get one tick after 10 seconds. That means you used 3600 <br>joules in 10 seconds (which is an average of 360W during 10 seconds). When <br>you update your database, RRDtool computes a rate of 360 and works with that <br>during the normalization and consolidation phases.<br><br>See my site ( <a href="http://rrdtool.vandenbogaerdt.nl/">http://rrdtool.vandenbogaerdt.nl/</a> ) for some information.<br><br></blockquote><br>Thanks a lot for pointing me into the right direction. I read the part about "Rates, normalizing and consolidating" and it all became clear :)<br><br><blockquote type="cite">Your step size is important when considering how much detail you want/need. <br>You could set it to 1.<br></blockquote><br>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. <br><br>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. 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? <br><br>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?<br><br><blockquote type="cite">Your heartbeat value should be large enough to not miss updates that happen <br>to be far apart. If all consumers in the house are off, almost no power is <br>used. Your measuring device itself is the only one. Compute how long it <br>takes for it to consume one Wh, double that time just to be sure, and set <br>that as your heartbeat value.<br><br></blockquote><br>I set the heartbeat to 14000, as the device uses 0.5w/hour which gives me 7200 seconds between ticks.<br><br>Thanks!<br><br>KR,<br><br>Oliver</body></html>