Single Phase DIN rail WIFI energy meter / circuit protection

Just discovered about this smart energy meters.
Different models exist on aliexpress: ZMAi-90 / Hiking DDS238-2 WIFI

Any one removed the cover of this cheap WIFI energy meters to see its guts ?
They seem to be upgradable to custom firmware (tasmota). Anyone using it with EmonCMS ?

Meter will update the kWh data even when disconnected from wifi.

Remote Control ON/OFF by Tuya app or Smart Life app at anytime from anywhere
Total active energy kWh measur.

App can read kWh, R.M.S current, voltage, active power
Timer control function
Delay time cut off function
LCD display, Real-time display of:

  • Voltage, Current, Active Power, reactive Power, power factor, frequency, total Energy kWh
  • Power Supply: 90-300V AC 50/60Hz
  • Rated Current: 65A
  • Pulse Frequency: 1600imp/kWh
  • 35mm Din Rail install
  • Can use the TUYA app, compatible with other TUYA products such WIFI socket, led, fans, etc.
  • Active energy accuracy is class 1, IEC62053-21

Note: This meter Only supports 2.4GHz Wireless Network, i.e. it has NO 5GHz support.


Just purchased “Tuya Single Phase Din Rail WIFI Smart Energy Meter timer Power Consumption Monitor kWh Meter Wattmeter 110V 220V 50/60Hz”

Anyone know if it’s possible to access/download hourly readings as .csv or similar?

Integration with Tuya app seems pretty basic.

Welcome, Harley, to OEM.

The answer to your question is most likely that the WiFi protocol they use is probably their own, and you’re unlikely to be able to find enough details to be able to program another device (for argument let’s say a Raspberry Pi) to interrogate it and handle the data as you wish.

Do you have any other useful information about the device - e.g. what are the two green terminals I can see? They don’t tie in with an on-line manual I managed to find (Hiking DDS238-2 User Manual (Page 4 of 4) | ManualsLib) but that does state there’s S0 output and RS485 - but nothing more.

Unless there’s more information forthcoming, you may face quite a struggle to get any information from it in a form you can do something with.

So my best suggestion, in the absence of more information - is to use the S0 pulse output (IF that’s the two green terminals) and count the pulses, using possibly an emonPi to then handle to conversion to power and energy (though it has to be said - whilst it’s as accurate as the meter (provided the power flow is unidirectional), pulse counting is only good for total energy, it isn’t very satisfactory for knowing instantaneous power.

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Hi Robert, thanks for your response.

Tuya Smart app connects - see screenshot - but only gives daily readings. Aiming for hourly data if possible.

Device manual says terminals 5,6 are impulse/kWh so I could hook those up to an emonPi, although that does seem to be duplicating the task of the gadget itself.

That’s pretty much what I was afraid of. As I wrote above, if you can’t find anyone who has picked apart what it’s doing in the WiFi band, then the hope of going beyond what the display or their software is prepared to give you is minimal.

You are correct - feeding the pulse input into a RPi does largely replicate most of the user functions of the device. Were it to have an RS485 port, I think you’d have stood a better chance of accessing the data shown on the leaflet.

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According to the datasheet, (and your post)

it does have an RS-485 port. (says it supports Modbus)

Unfortunately, I don’t see any reference to a register map.

Register map info here:

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I read that too - but the leaflet/screenshots that @Halsteads posted make no mention of the port, only the S0 pulse output. So methinks it’s been “cheapened” with WiFi instead/only. Or there is a different version. Only the first of Nuno’s links above appears to have both.

(And somebody needs to tell whoever wrote that app that “K” is degrees Kelvin, not the multiplier kilo. What quantity does degrees Kelvin × power × time represent? :exploding_head:)

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Quite right. I pulled the info from the link you posted.

We need @Halsteads to tell us what there is in addition to the main (60A) terminals.

I’ve a few converted to tasmota and posting to the emoncms api directly.
Requires opening and reprogramming them.

The one at that link is NLA. :frowning_face: Viz:

One other thing that hasn’t been mentioned…
The meters are direct connect. i.e. they don’t use a CT.

From what I can tell, only the Hiking DDS238-2 ZN/S variant is RS-485/Modbus capable.

Thanks Robert and Bill,

Correct, the Open (mfr) unit I purchased doesn’t have RS485. Pulse output and WiFi only.

Exactly so.

My hopes that I could get data I needed using WiFi are dashed, which takes me back to the drawing board. But I think I’d better start a new thread on that.
Thanks again for help and thoughts - much appreciated.

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It might just be worth downloading a LAN ‘sniffer’ program to see if the data is recognisable, I say there’s a choice of two - it is and it’s much like the Modbus registers (why make it different), or it’s still like the Modbus data but encrypted. My money would be on encrypted, and the key is exchanged when the unit is paired with the app.

Now if you’d read about the Modbus-enabled meters that we know about…

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As this is a Tuya device, potentially HomeAssistant could connect.

There is an interface library created by Tuya for HA but this device class does not seem to be on the device list.

You could Open an Issue and see if they get included, if it is integrated with HA, then getting the data to EmonCMS is easily done.

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thanks Brian, I’ve had some dialogue with Tuya, but they say it’s entirely up to the manufacturer.
I’ve tried to contact seller (I know they have direct link to manufacturer) and will ask about HA.

True, except if it does connect to the App, it must be using a standard protocol so it is likely the Python Library can read the data. Perhaps what they mean is it is up to the manufacturer how often it sends the energy data.

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Remarkably, I got a response from the mfr:

Hello, this product cannot download readings We are preparing a new product that may suit your needs