logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

[BK7231N / CB3S] Atorch AT2P - "HD Color Screen" DIN-rail relay/energy meter with RS485

js9658850 1692 15
ADVERTISEMENT
Reply Cool? Ranking DIY | New topic
Notify about new articles
📢 Listen (AI):
  • Teardown of this energy meter from AliExpress https://www.aliexpress.com/item/1005004917583615.html

    Electrical energy meter with a display showing various measurement data.

    The overall build quality is excellent. The screen is bright and clear, and the device offers a full set of features. However, there are a couple of drawbacks:
    •The RS485 interface does not use Modbus; instead, it relies on a proprietary protocol developed by Atorch.
    •The device is not bi-directional, meaning it cannot measure exported power. This I believe to be a software limitation.

    Atorch electrical energy meter with a display and buttons for DIN rail mounting.
    Front of an energy measurement device with visible inputs labeled N-IN and L-IN.
    Nameplate of an electricity meter from AliExpress

    Opening the device is simple, remove the locking mechanism and 2 Philips screws.
    Back of an electronic module case with a label, open space for the screw.

    Once opened, the construction appears high quality. The daughterboard is connected via a 10-pin standard interface, the power electronics are well-arranged, and there's a small beeper for audible alerts.
    CB3S module on a green board with electronic components.
    Interior of an electronic energy meter.
    Interior of an energy meter showing a circuit board and wiring.

    The meter contains a CB3S TuyaMCU, which is responsible for WiFi connectivity and integration with the Tuya Cloud/App. This connects via UART to a secondary CH573F MCU, which handles power monitoring, screen, buttons and RS485 communication. Pins 1 and 2 are TX and RX for RS485.
    Close-up of CB3S module on a printed circuit board with labeled pins.

    The RS485 module works directly with ESPHome if you connect Pins 1 and 2 to RX/TX respectively (I have tested this) and it works fine as long as a 120 Ohm resistor is placed across A and B.
    Close-up of a circuit board with electronic components and labels.
    If Pins 1 and 2 were disconnected from the CH573F and instead connected to the CB3S TuyaMCU, Modbus control via ESPHome could theoretically be enabled.

    This IC seems to be there for 3.3V DC power regulator:
    Close-up of a circuit board with visible chips and markings.

    One key IC is the AC power metering chip, but unfortunately, all its markings have been removed. I have attempted to mark it as best as possible. If anyone can identify it, please let me know!
    Interior of an energy meter with visible printed circuit board and pin labels.

    I still have the device and it is currently unused. If anyone has questions or wants me to de-solder the TuyaMCU to read the flash, or perform any other modifications, let me know!

    Cool? Ranking DIY
    Rust on Embedded Online Conference on 16 July with 33 per cent discount for elektroda users
    About Author
    js9658850
    Level 2  
    Offline 
    js9658850 wrote 3 posts with rating 2. Been with us since 2025 year.
  • ADVERTISEMENT
  • #2 21419752
    p.kaczmarek2
    Moderator Smart Home  
    Thank you for this interesting presentation!
    Would you be able to dump the 2MB Flash of the BK7231 module?
    https://github.com/openshwprojects/BK7231GUIFlashTool
    This would be very useful for us, as that could be used to extract data points information: TuyaMCU guide
    I didn't see this Atorch device yet, so far I had only Atorch plug with similiar screen: https://www.elektroda.com/rtvforum/topic4088414.html

    PS: Have you tried using this RS485 interface?
    Helpful post? Buy me a coffee.
  • ADVERTISEMENT
  • #4 21420295
    p.kaczmarek2
    Moderator Smart Home  
    I think I may need to go through all the topics and check if each has entry on list... because we sometimes forget about it.
    Helpful post? Buy me a coffee.
  • #5 21420305
    divadiow
    Level 34  
    yes. I have caught quite a few by going back through, but there's undoubtedly more, I wasn't terribly methodical.
  • #6 21420310
    p.kaczmarek2
    Moderator Smart Home  
    I can get a list of all topics in IoT section and then write a little script to compare it with what we have on Teardowns List, would that help?
    Helpful post? Buy me a coffee.
  • #8 21422467
    mfac
    Level 17  
    Not so cool at all. It has a residual current protection option, using an external transformer. The trouble is that although this function is disabled, or even if there is no transformer, this protection causes unnecessary trips every few minutes. Neither short-circuiting the input nor inserting a capacitor as a filter helps. Such a defect was revealed to me in one of the two units I own. The meter sees supposed leakage currents of a few hundred mA.
    Navigating the menu is also tedious for me.
  • ADVERTISEMENT
  • #9 21422473
    p.kaczmarek2
    Moderator Smart Home  
    Maybe a faulty copy? Isn't there an option to turn it off?
    Helpful post? Buy me a coffee.
  • ADVERTISEMENT
  • #10 21422803
    mfac
    Level 17  
    p.kaczmarek2 wrote:
    Maybe a faulty copy? Isn't there an option to turn it off?
    .
    There isn't. You can only raise the threshold, but the maximum is probably 300mA, but that's not enough.
  • #11 21431308
    js9658850
    Level 2  
    @p.kaczmarek2 >>21419752

    As requested, I have de-soldered the MCU and performed a firmware backup. I presume this is what you were looking for.
    readResult...-46-31.bin Download (2 MB)

    Also, Atorch is sometimes branded as HiDANCE, which I believe is the same company.

    I have tested the RS485 interface, and it works fine with their proprietary software. However, as mentioned before, it does not use Modbus but rather Atorch's own communication protocol. It is possible to make it use Modbus over RS485 by connecting the RS485 to your own MCU.
  • #12 21431320
    js9658850
    Level 2  
    >>21420255

    It is a very similar device! I believe Atorch is sometimes branded as HiDANCE, which seems to be the same company. However, that particular unit doesn’t include RS485, and some of the PCB layouts are different.

    Added after 5 [minutes]:

    >>21422467

    Interesting fault you found. The unit I have has the residual current protection option disabled, and I haven’t experienced any trips. How long did it take before a trip would happen? Did you have any load on the device when it occurred, or would it happen even if the device was idle?

    I also agree—the menu is a pain to navigate!
  • #13 21431334
    divadiow
    Level 34  
    >>21431308

    hefty list of dpIDs for this device

    Code: Text
    Log in, to see the code
  • #14 21432896
    mfac
    Level 17  
    js9658850 wrote:
    Interesting fault you have found. The unit I have has the residual current protection option disabled and I have not experienced any trips. How long did it take before the trip occurred? Was the unit loaded when the fault occurred, or did it occur even when the unit was idle?
    .

    It was loaded, I also don't rule out that it might have scored some sort of short circuit.

    Do you know how to turn it off?
  • #15 21569997
    franciscowmorante
    Level 1  
    >>21422467 Hello, good morning. I'm having problems with something very similar. It makes it impossible to use the device, as it only displays "Lakage Protection" and doesn't allow me to do anything else, I've even deactivated it. Have you been able to do anything? I tried to find a solution or a clue where to start. I tried to contact Torch's technical support via email, but they haven't responded at all. I'm confused. I would try to reset the firmware to see if this option is disabled.
  • #16 21570259
    mfac
    Level 17  
    >>21569997 No. I removed it and put the old meter back in.
Reply Cool? Ranking DIY | New topic
Notify about new articles
📢 Listen (AI):
Report a violation of the law

Topic summary

The Atorch AT2P energy meter, featuring a bright HD color screen and DIN-rail mounting, was disassembled revealing high build quality and a BK7231N MCU with 2MB flash memory. The device uses a proprietary RS485 communication protocol rather than standard Modbus, limiting interoperability. Firmware dumping was performed to facilitate data extraction and analysis of device datapoints (dpIDs). The meter supports various parameters including voltage, current, power, leakage current, and pricing modes. A notable hardware/software limitation is the lack of bi-directional measurement, preventing export power monitoring. Some units exhibit a problematic residual current protection feature that causes frequent nuisance trips even when disabled or without an external transformer; this protection threshold can be raised but not fully disabled. Navigation through the device menu is considered cumbersome. Attempts to resolve the leakage protection fault via firmware reset or manufacturer support have been unsuccessful. Atorch is sometimes branded as HiDANCE, with similar but not identical devices. The RS485 interface can potentially be adapted to Modbus by interfacing with a custom MCU. A comprehensive list of device datapoints was shared, aiding in further firmware and protocol analysis.
Summary generated by the language model.
Popular Topics
ADVERTISEMENT