What's happened to emonTx V4?

Just wishing to add my ‘1 pennies worth’,… and not wishing to offend anyone,…
Brians comments re HA,… I use an ESP32,… with 4 DS18B20,… connected via the openenergy expansion board, Tasmota connects and then shares with HA,… HA then shares with emonPi… the temperature monitoring has not missed a beat I have several of these Tasmota / DS18B20 configs and they all work very reliably,… ( well so far,… 12 months+ ), and as final note on temperature monitoring,… I prefer to have the most accurate power measurements,… rather than compromise a little and get temperature recorded, but just my pref.
Bills link to the ‘expanadable 6 x CT monitoring,. using an ESP32’,… it may not be as accurate as emonTx’s,… but it is actually quite good and compact on the face of it,… and does offer a chance to do monitoring of a system if required, it never hurts to see what the competition has to offer, in order to stay ahead of the game…
Also taking a ‘lessons learnt’ from emonTx4 and the 6CT expansion board,… can the powers that be make ‘mechanical provision’ for the mounting and securing of this daughter board,… and any other board,… so as not to stress connectors,… with unnecessary mechanical loads.


The new emonTx5 top fascias and 12 CT fascias for both the emonTx5 and emonPi2 have arrived!

I’m curently working through rationalising the firmware’s so that we have single set of firmwares that are compatible across the emonTx4, emonPi2 and emonTx5 range with only a #define compile option when compiling firmware for these three hardware variants. This also highlights how similar these variants are and ensures that further firmware developments are available for all three hardware units.


2 posts were split to a new topic: Trouble with TX4 and temp sensors

I can appreciate the view @borpin that the temp sensor question was off-topic, but the primary question was FW so would be on-topic? In any case for anyone interested in status of FW I put the link to Trystan’s reply that was moved here:

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The title of the thread is 'What’s Happened to emonTX4" so a general firmware question doesn’t seem to be the same subject.

We are getting ready for the emonTx5, I’m part way through updating the emonTx4 and emonPi2 documentation to reflect the new common base firmware across all three devices including the emonTx5.

I’ve taken the opportunity to update the system overview page, quite pleased with those icons :grin: . plus hopefully a clarifying paragraph on how these units relate to each other. I’ve also updated the side bar menu with clearer categories.


It the TX4/Pi2 only 6 channels? If not I’d add here that optionally 12 channels as that may be a key buying decision.

Thanks @borpin the expansion board up to 12 CT sensors is noted in the paragraph above the items, but I could also add that in on each item if you think that would be clearer? I’ve also adjusted the wording a bit more since my post last night, to highlight how the emonTx5 can be used to extend an emonPi2 system and how the emonBase can be used as an alternative base station.

I think it could still be clearer to highlight that is is possible to extend the number of CT sensors on an emonPi2 that has a Pi Zero to 12 CT inputs and that if further channels are required at that measurement location that an emonTx5 is then a good option either with an additional 6CT sensors or 12CT sensors to bring to 24…

Alternatively for folk who would like a full RaspberryPi 4 with USB and Ethernet in their emonPi2, extending to 12CT or 18CT channels is also possible with 6CT channels on the emonPi2 and 6-12CT channels on the emonTx5…

I have been thinking about this a bit lately, I’m in too deep to not get it all, but when you recommend OEM to someone I now get a lot of questions back about what does what etc (even the nerdy people!).

What about a table of some sort that has a summary?

Column 1 Column 2 Column 3 Column 4
CT Supported Temprature Sensor Pulse Counter
EmonTX3 4
EmonTX4 6 (12 optional) 3 (0 with 12CT) Up to 2
EmonTX4 Pi Zero 6 (12 optional) 3 (0 with 12CT) Up to 2
EmonTX4 Pi4 6 (12 optional) 3 (0 with 12CT) Up to 2
EmonTX5 6 (12 optional) 3 (0 with 12CT) Up to 2
EmonTX5 Pi Zero 6 (12 optional) Many? Uses Pi? Up to 2
EmonTX5 Pi4 6 (12 optional) Many? Uses Pi? Up to 2

From my perspective, saying the TX can transmit the data via Wi-Fi would be a key buying decision. No need for a base or Pi (additional cost).

I think the important bit is that this is your sales pitch, not just a technical summary.

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Sounds good, here’s an amended version, I’ve included firmware here as that’s a key determinant of what is supported:

Hardware Firmware CT’s Channels Temperature Sensors Pulse
EmonTx4 emonTx4_CM_6CT_temperature 6 3 (6 optional) 1
emonTx4_DB_6CT_1phase 6 0 1*
emonTx4_DB_6CT_3phase 6 0 1*
emon_DB_12CT (1-3 phase) 12 0 3*
EmonTx5 emonTx5_CM_6CT_temperature 6 3 (6 optional) 1
emonTx5_DB_6CT_1phase 6 0 1*
emonTx5_DB_6CT_3phase 6 0 1*
emon_DB_12CT (1-3 phase) 12 0 3*
emonPi2 (Zero) emonPi2_DB_6CT_1phase 6 6+ (Pi) 1*
emonPi2_DB_6CT_3phase 6 6+ (Pi) 1*
emon_DB_12CT (1-3 phase) 12 6+ (Pi) 3*
emonPi2_CM_6CT (current only) 6 6+ (Pi) 1
emonPi2 (Pi4) emonPi2_DB_6CT_1phase 6 6+ (Pi) 1*
emonPi2_DB_6CT_3phase 6 6+ (Pi) 1*
emonPi2_CM_6CT (current only) 6 6+ (Pi) 1

The pulse sensor * denote standard firmware radio packet support for the number of pulse sensors given. Firmware modification can extend the number of pulse sensors to 3 on all emonLibDB based firmwares.

If you add a Pi Zero to an emonTx5 for WiFi you basically end up with an emonPi2 (Pi Zero) there’s no real difference in cost there unfortunately. The ESP8266 adapter that we stocked with the emonTx4 was also not that different in cost to an Pi Zero…

I’ve been going through the emonTx4 heat pump monitor application guide this morning updating it for the new firmware, not sure how many folk have tried using an emonTx4 for this or followed the guide there but there’s some good information in there if anyone is interested in using one of their emonTx4’s for this EmonTx4 Heatpump Monitor — OpenEnergyMonitor 0.0.1 documentation

The same process will be applicable for the emonTx5 as well and mostly the same for the emonPi2 (appart from temperature sensing being handled by the Pi).

I already have an emonHP so was just having a look at that page out of interest.

Where it says about the Ecodan wiring mine is quite different.
My ASHP is connected back to the consumer unit for power, as per what it says on that page.
However my FTC6 Controller doesn’t have its own power source (despite being next to the consumer unit) but instead it is powered from the outdoor unit down a cable that combines power and signal lines between the two.
The system pump and 3-port valve are then powered from the FTC6.
So for power its CU → Ecodan Outdoor Unit → FTC6 → System pump and 3-port valve.

The immersion is via an Eddi with its own power with the FTC6 connected to the eSense input on the Eddi Relay board so no current draw.

Therefore my Electricity Meter connected to emonHP is just after the CU on the power cable off to the Outdoor unit so this is measuring everything but the immersion.

Don’t know if it is worth updating the docs to say this is another way they are wired up.

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What you are saying then, is that the TX should be regarded as an emonPi2 extender. Perhaps it should be marketed as such.

Agreed, this is how I’ve described it here:

It’s also possible to use it with an emonBase rather than an emonPi2 of course, here’s the emonBase description:

This is all very much following the long running system configuration tradition that we have had here at OpenEnergyMonitor of course.

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Thanks @ajdunlop I will have a look at that, cheers!

A couple of better pictures of the emonTx5:

6 CT configuration:

12 CT configuration:

Temperature*, USB serial, emonVs and analog ports:

*The SD card slot is not applicable to the emonTx5 as there’s no RaspberryPi inside - this is a RFM69 433Mhz radio transmitter node only. These are the same back and front fascias as used for the emonPi2, we are only changing the top fascia to have the specific emonTx5 branding.

*Temperature sensing is only available when using the single phase emonTx5_CM_6CT_temperature firmware based on the emonLibCM library. There is a slight impact on electricity monitoring accuracy when using temperature sensing, see forum post for the emonTx4 here.


I’ve listed the emonTx5 in shop as available for pre-order while I finish the documentation over the next week emonTx5: 6-Channel Energy monitoring transmitter node - Shop | OpenEnergyMonitor. Suggestions for improving the listing are welcome.