emonTx5 transmitter node & emonPi2 (12 CT expansion) available in the shop

I’m happy to announce that the emonTx5 transmitter node & emonPi2 with 12 CT expansion option are both now available in the shop :tada: (Since Monday 27th of May of course for those already aware :slight_smile: ) . The emonTx5 can also be expanded to 12 CT inputs with the expansion board option if required.

There are now single shop entries for single-phase, 3-phase, N.American split phase and current only options. The CT expander can also be selected from the option list (though the additional up to 6 CT sensors need to be added separately)

System arrangements

This update brings back the system versatility offered by the long running system arrangement options that we’ve had here of an emonTx transmitter node and an emonPi or emonBase base station (while offering the potential for a much larger number of CT inputs than previous generations at both the emonTx and the emonPi locations alongside full 3 phase support). Thanks to @whitecitadel and others for making the point that the Tx option was missing! What's happened to emonTx V4? - #5 by whitecitadel.

I have covered some of the main system arrangements that can be achieved with the emonTx5 and emonPi2 on the emonTx5 documentation page here: https://docs.openenergymonitor.org/emontx5/install.html.

  1. emonTx5 and emonPi2 in different locations
  2. emonTx5 and emonPi2 in the same location with shared emonVs
  3. emonTx5 and an emonBase base-station

We are also stocking an RJ45 Duplicator for applications that can benefit from a shared emonVs here.

New front page
To try and make it simpler to understand what we are offering we have reworked the OpenEnergyMonitor front page to highlight the way the different OpenEnergyMonitor system components can fit together. See: https://openenergymonitor.org/ & forum post: OpenEnergyMonitor.org front page revamp.

Common AVR-DB base firmwares for the emonTx4, emonTx5 & emonPi2 family
This update also includes updated firmware for all three AVR-DB hardware variants - mostly to create a single set of common base firmwares from which the particular emonTx4/5 & Pi2 variants are built from. See forum post emonTx4, emonPi2, emonTx5 14th May 2024 firmware release for more details. It’s worth also checking the table of firmware options for each hardware variant:

Thank you to everyone who have given feedback and input on the documentation, shop entries and firmware over the last few weeks.

There are certainly more documentation pieces that will no doubt be good to add or refine. Please let me know if there’s a particular element that needs clarification and I will do my best to help.


I think the new table on the firmware page makes it much clearer the options and the compromise between electricity and temperature monitoring :+1:

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Thanks @whitecitadel Im glad to hear that and thank you for the suggestion!

This is awesome, Trystan. Can you say more about what the N American split phase unit would include? I’d like to update the “emonTx in N America” thread I’ve been using to keep track of the evolving shop options. emonTx V4, emonVS in North America - Hardware - OpenEnergyMonitor Community. The last update in there at this moment is from Dec 2023 from the time-window when no emonTx (only emonPi) options were available in the shop.

I’ve been tracking things in terms of a “technical user” that would go to the extent of monitoring both legs of the split-phase with an emonVS, assigning to each CT the correct leg/phase according to the physical connection in the breaker panel. And a “non-technical user” that would use a NEMA 5-15P cable with the emonVS, plug it into an outlet, and do what we’ve historically done with single-phase firmware and an AC-AC adapter (in the emonTx3 era.)

These are the users I have in mind when I wonder what comes with the N America option in the shop.


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Thanks @brandock and all credit to @Robert.Wall for highlighting that we should make this a clear shop option and also doing the hard work to support the N. American split phase configuration in the emonLibDB library!

Reading your useful thread, this is exactly what we are offering with the N. American configuration, a 3-phase emonVs and firmware pre-uploaded to use 2 out of the 3 voltage sensors (the technical user configuration as you describe it):

Edit: removed bit about correction, I misread :slight_smile:

I was planning on starting a thread about this as one thing we haven’t settled on yet is what should the standard CT sensor to voltage sensor allocation be? can there be a standard allocation or will it always end up needing an installation specific configuration?

Do we standardise on a couple of 240V line-line loads and the rest being single phase alternately allocated to leg 1 and leg 2?

First of all, for N America you would have to standardize, not standardise. :wink: But in answer to your question, I am of the opinion an installation-specific configuration will be necessary. A number of the most important loads will be the line-line loads (they are the big energy users such as EVSE, air-conditioning, electric oven, electric dryer) but that will depend on which and how many of these an individual has. And with 6 CT inputs there will inevitably be an assortment of remaining channels that use only leg 1 or leg 2 but could randomly all happen to be on leg 2.

I think this will work out OK because our “technical user” will readily be able to understand and configure this. In particular, if I have the requisite skills to connect an emonVs to each leg inside my breaker panel, then I will have the requisite skill to identify which leg (or legs) each monitored circuit is connected to.

(It would be cool if the configuration of which is connected to which could be done in the software, without uploading new firmware. I haven’t seen that this is possible yet, but I may not be up to date on that.)

I think it would be worth considering a “non-technical user” package in the Shop as well. The main difference would be the emonVs would have the US plug (NEMA 5-15P cable) and the firmware would expect to monitor only one leg. The emonVs would be used in place of the old AC-AC adapter. This would not require hiring an electrician (and explaining to an electrician what the heck one is trying to accomplish) or acting like an electrician by installing wires into breakers inside a breaker panel. To monitor both legs, there’s a difference between knowing what needs to be done (I do) and knowing how to do it safely (I am much less confident of this).

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Thanks @brandock

This is a very good point, I will discuss this with @glyn.hudson and see what we can do.

One thing to be aware of…

The National Electrical Code (NEC 725.136A) specifically excludes any low voltage wiring from being installed in an electric panel, raceway, or box used for high voltage (120/240V) circuits.

Low voltage in this context, means less than 50 Volts.

I’d like to discuss that further over in that topic to keep things together. I will bring it up over in that thread.

I think this is yet another reason to have the “non-technical” option for N America: I think it is not entirely clear yet what a safe, up-to-code installation is going to look like to monitor both legs of split-phase N American power with an emonVs.