Questions about extending my existing system from 2022 with a new emonTx4

I am in the US. I have an emonTx3 and emonBase purchased in January 2022 with 4 CT current sensors. The emonTX does not have Wifi. The emonTx3 is powered by an ACAC adapter with a US plug on US 120VAC 60Hz power.

I have been using the system to monitor 3 240VAC circuits in my main distribution panel. And this whole system works.

I want to expand the system with another emonTX located a good distance away from the original emonTX and the emonBase. It will be located at a water filtration and booster pump on the far side of a separate garage building.

This additional emonTx system will be monitoring the power used by a 240VAC 1HP booster pump and also logging pulses from a water filtration system.

The documentation Adding an emonTx4 to an existing installation — OpenEnergyMonitor 0.0.1 documentation says I can add an emonTx4 to an existing emonBase installation using either a direct USB data connection or 433MHz radio data connection. It doesn’t offer Wifi as an option.

I think that Wifi would be a better way to communicate between a new emonTX and the existing emonBase because I have good Wifi coverage through a number of Ubiquiti Unifi Wifi APs. I am doubtful that the 433MHz radio will work from the proposed emonTx4 location to the existing emonBase location. I had problems before between the emonTx3 and emonBase, and I had to move the emonBase closer to the emonTx3.

My existing emonBase is apparently using a Raspberry Pi 3 B Rev 1.2 - 1GB
emonpiRelease: emonSD-21Jul21.
EmonCMS version: low-write 11.3.22
I am not certain if my emonBase is RFM69-SPI or RFM69Pi. I don’t find this info in the emonCMS system info.


Can I use the emonTx4 to extend my system and use Wifi communication to log the data to my emonCMS on my emonBase while continuing to use 433MHz communication to my existing emonTx3?

Do I need an emonVS or can the emonTx4 be powered by USB? It doesn’t seem the emonVS is available with a US plug. Can I wire my own US plug?

To the best of my knowledge, it’s not in full production yet. It’s worth emailing The Shop to confirm - [email protected].

Yes. It goes into the Pi via your LAN, not the serial or SPI ports like the ISM band radio.

This won’t affect anything outside of the emonBase.

You can certainly put your own plug on the cable - or your own moulded plug & lead (3-core, grounded) into the terminal block, the emonVs works from below 88 V upwards, so fine on 120 or 240 V. If you DON’T have the emonVs, you only get current and a guess at apparent power, which for a pump (induction motor) is likely to be way different from the power you pay for (real power). If you’re prepared to accept that, then you can power the emonTx4 via USB. Or you can have the emonVS-mini: UK Plug - Shop | OpenEnergyMonitor (and the Shop might take the UK plug and lead off if you ask to save on shipping costs) and use this with a USB power supply.

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