How to get started with a new system

Hello Trystan,
is it possible to get a TL;DR for a guy who would like to get rolling without having yet bought any of the old equipment ? I see in the shop that I can order the web station. What is coming next week and how can I build a working system out of it ?
Best regards,

Hi Marc, welcome - I moved this question to a new topic.

The EmonTX is a device for measuring power, energy and (to a limited extent) temperature. The measurement (both import & export) is done by attaching CTs for power & energy.The TX4 will have the ability to monitor 12 circuits of varying power rating and 3 temperature sensors. It can also measure the energy as indicated by the LED pulse via a pulse sensor, but an EmonTX to just measure pulses is a waste of money.

The measured data can be sent to any system you like, but usually this is EmonCMS (OEMs monitoring software). This is most usually installed on an RPi using the prebuilt image, but with the paucity of supply of RPis, you may need a different solution (unless you have a spare one kicking around). EmonCMS will run on a PiZero, but in all cases we recomend you do not install other software on this Pi.

Personally I run EmonCMS primarily in a PVE LXC container on a laptop.

There are several methods of getting the data out of the EmonTX. In the past this was most usually via the onboard RFM69 chip that sent the data to another RFM chip on an EmonBase. The EmonBase is simply an RPi with and RFM Board attached to receive the data.

The EmonTX4 will have more options and personally I’d recommend an ESP device or possibly the PiPico. You can also connect an RPi (or anything that can read serial data) directly to the EmonTX via the serial output or even the USB port on the TX4.

I’m currently working on some software to use a cheap ESP8266 (Wemos D1 Mini) and ESPHome as the communication mechanism over Wi-Fi. This will have the added advantage of adding HomeAssistant integration ‘out of the box’.

OK cheers. Will read up on all that.
You say 12 circuits but this says 6. Is it shipping as six out of the box ?
Since I need two TXs I would guess that the most economical way is to buy a EmonBase and be rolling on delivery but I would be interested in integration with HomeAssistant (although this is maybe possible with the Base anyway).

Yes, the emonTx V4 has 6 × current inputs as standard.

There is an add-on board in development that could potentially increase that to 12. Work is still ongoing on that. @TrystanLea


@Gwil - do you have a stock of RPis for EmonBases/EmonPis? I’d thought they were out of stock.

There can be problems with RF communication over the RFM chips with multiple TXs. A search here may reveal some threads; I came across this comment today on the subject How to match a ttyUSBX device to a USB Serial device - #9 by gadgetbazza.

I think Robert has done some work to try and mitigate this, but I’d advise not trying to use 2x TX communicating via RFM.

ok thanks for saving me a headache

Indeed, it’s in latest version of my RF library rfmTxLib (NOT in JeeLib) and the concept is to “sniff” the band to see if another transmitter is within range, and if so, wait until it stops. It’s not foolproof - the other transmitter can be within range of the receiver but not our transmitter, and then it doesn’t work. But if you have transmitters close together, then it will alleviate the situation. The problem is, none of the r.f. libraries that I know of work on the master-slave principle, which would solve the problem. But that in itself isn’t suitable for (say) the emonTH because it’s expensive in battery power, as it needs the receiver to function continuously (or for a significant period when it expects to be talked to) to be able to know when it’s being asked to send its data.

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Yes, we now have Raspberry Pi 4’s in stock ready to be used.

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Could the shop be updated to say which version of the Pi is being supplied, please?