What is the EmonTx actually recording ? is it Wh?

Now I get it.
If you want the daily total energy, then what you’re doing will give a good approximation (as good as the accuracy of the emonTx combined with the sample being representative of the power between that one and the last).

If you change to the Continuous Monitoring software, the numbers you’re logging into your database every 5 s will have been derived from about 10,000 measurements inside the emonTx, but the sketch accumulates those internally anyway and sends the cumulative total so far every 10 s (by default - change it if you wish). If nothing is lost in transmission, the cumulative total at midnight less the one from 24 hours ago will match the last day’s value from your database.

This is a bit far-fetched and unlikely in practice, but if something uses a short burst of energy every 5 s and it always falls between samples of the discrete sample software, it won’t be recorded, whereas the CM software (and your electricity meter) will see and record it.

I explained how emonCMS does it, simply because most people writing here use it, and you didn’t say otherwise. In fact, you’re making exactly the same assumption - and it’s nothing to do with emonCMS, it’s derived from the way the emonTx (the old discrete sample library) works, and that’s because it was originally conceived to operate primarily from batteries - so a 200 ms sample every 10 s was a power-saving technique.

Thanks Robert,
So I’ll Definitely update to the New Continuous software First.
Is there an Idiots guide anywhere. When I googled it all I got were people having problems?


If you use the present default sketch, it should work for you if you have an emonTx V3.4. If yours is a V3.2, you will need to do some work on the sketch - either you need to keep your RFµJeeLib, or swap to rfmTxLib. Glyn & Trystan have never published a sketch for the V3.2 (although I’ve tested the library on one).

Is there a way for me to find out my version ? I don’t have any record of it.

Look at it! It’s on the silk screen, or the dead give-away is the emonTx V3.2 has three layers of circuit boards! The main board carries the connectors and a few SMT components. Piggy-backed on that is the RFµ328 module with the processor, piggy-backed on that is the RFM12B.

The emonTx V3.4 has two layers: the processor and SMT parts are on the main board, with just the RFM12B or RFM69CW sitting on it. Take a note of which radio you have, because there’s a software switch to set up the right section of the library to control it. There are pictures: Learn→Electricity Monitoring→Networking

Ok Thanks