WEB- U2 USB Meter/Monitor UPM Quick Look

Official specifications

  • Product Model: U2
  • Voltage measurement range: 4-24V
  • Voltage measurement resolution: 0.0001V
  • Current measurement range: 0-5A
  • Current measurement resolution: 0.0001A
  • Capacity accumulation range: 0-99999Ah
  • Energy accumulation range: 0-99999Wh
  • Temperature range: -40℃~180℃ / -40℉~356℉
  • Display screen: 1.77 Inch color TFT 128×160 display
  • Product size: 52.5mm x 34.5mm x 13.0mm

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Interface #1.1 Simple interface and large font
Interface #1.2 Six-digit display
Interface #2 Capacity and Energy
Interface #3 Equivalent Resistance
Interface #4 Fast Charging Protocols
Interface #4.1 Confirmation of Entering Trigger and Detection Menu
Interface #4.1.1 Trigger and Detection Menu
Interface #4.1.2 Trigger and Detection Menu
Interface # Auto Detection
Interface #5 Summary
Interface #6 Cable resistance measurement
Interface #7.1 V/A Curves
Interface #7.2 D+D- V/A Curves
Interface #7.3 Offline Data Curves
Interface #8.1 Settings
Interface #8.2 Settings
Interface #8.3 Settings

PC Program


You may need an on screen translator.


Current Accuracy (Brightness Level 1, Loaded)
V A Display A
5 1.00145 0.99942
1.50035 1.49757
2.00060 1.99643
9 1.00145 0.99944
1.50045 1.49725
2.00060 1.99652
12 1.00145 0.99958
1.50095 1.49784
2.00060 1.99642
20 1.00161 0.99957
1.50125 1.49823
Voltage Accuracy (Brightness Level 1, Unloaded)
V Display V (5 Digits) Display V (6 Digits)
5.04615 5.0448 5.04481
9.07260 9.0706 9.07061
12.1102 12.106 12.1067
15.1193 15.115 15.1156
19.9804 19.975 19.9758
Own Current Consumption
V mA, Display On mA, Display Off
Brightness Level 1, USB HID Port On
3.81 20.61 18.27
5.05 20.66 18.43
9.08 20.77 18.46
12.12 20.82 18.50
15.13 20.87 18.62
19.99 20.91 18.71
Brightness Level 1, USB HID Port On, w/ External Power
3.81 0.04 0.03
5.05 1.94 1.68
9.08 20.71 18.33
12.12 20.72 18.35
15.13 20.74 18.54
19.99 20.93 18.61
Brightness Level 1, USB HID Port Off
5.25 19.98 5.53
  • The accuracy of the current is good, but the voltage is not. The voltage needs to be recalibrated.
  • When brightness level is set to 1 and USB HID Port is on, own current consumption is around 21mA with display on and 19mA with display off. When USB HID Port is set to off, it becomes about 20mA with display on and 6mA with display off.
  • The internal resistance is about 32mohm (Includes both connectors).
  • The lowest working voltage is about 2.9V, but it needs to be read in the dark.


This UPM begins to consume external power once the input voltage is lower than the external supply voltage.

—- FW v2.4 —-

  • It behaves like a source with power limited when it triggers/requests the last PPS APDO. When the requested output voltage exceeds the nominal Prog voltage, the it limits the requested output current such that for a PDP Rating of x Watts the requested output current limit is calculated as RoundDown (x/requested output voltage) to the nearest 50mA. So you won’t get the max power even if the source is not PPS power limited.

UPDATE 8/14/2018

  • I overestimated its algorithm. When the requested power (output voltage * max output current) exceeds the PDP, it limits the requested output current such that for a PDP Rating of x Watts the requested output current limit is calculated as RoundDown (x/requested output voltage) to the nearest 50mA. Let’s say, PDP = 30W, Requested Output Voltage = 11V, and the Requested Output Current will be PDP/Requested Output Voltage = 30W/11V = 2.73A RoundDown to the nearest 50mA = 2.70A. So you won’t get the max power even if the source is not PPS power limited.


It has some software issues when powered by an external power source, but no such issues without an external power source.

The PD Listener loses packets even when using external power and operating correctly.

Ah and Wh calculation errors. This happens when USB HID PORT is turned off and the screen is off. Some data seems to be missing when the screen is turned off.


The highlights of this UMP are the interesting action recognition and g-sensor. Other than that, the rest is not very impressed. The factory voltage calibration is not done well. And the own current consumption is a little bit high when the USB HID Port is on. Also, the performance of drawing curves is not very good. In addition, the PC program is very simple and crude. However, new firmware is released often. Hope some of the issues will be fixed in the future.

Mutual Support

The following is a list of files discovered, created, modified, or provided by U2 users to help others. If you are a U2 user and would like to add your work to this list, please leave a comment or contact me.

Thank you all for your hard work!


69 thoughts on “WEB- U2 USB Meter/Monitor UPM Quick Look

  1. Good day. I hope this finds you and yours doing well. Thank you for all of the effort in putting this page together.

    Are Web- U2 and Witrn U2 the same hardware? I ask as I bought a Witrn U2 (non-BT) and am interested in 1) updating to the latest firmware, 2) to make use of a PC app, and 3) to manually install a BT radio.

    Also, it is appropriate that the Witrn site is pretty borked (29 Jun 2019), with only the link to the official manual existing thereon still.

    Please advise. Thank you. Have a great day!



    • Yes, the fake ones are capable of updating once an actual serial number has been applied to the device.

      If you hold down the OK button and then insert the microUSB cord into the device (while still holding down OK), it will go into PC mode. I just updated both of mine last night (one real and one fake) via the new PC app and network updating.

      Liked by 1 person

      • Honestly, I had someone connect to me and use their script to do it on their end. I have no idea where that person is or how to reach them anymore. Since then, I’ve purchased a legit WEB-U2 on Aliexpress. If anyone wants to know the seller, I can look it up.


    • If you don’t have a fake version all your questions have yes answer. You need a BT 4.0 ble module based on CC2541 chip, to connect to the application designed by QWAY for android.

      Liked by 1 person

      • Thanks, bikertibi. Understood. I have an original model, I believe (SN is not the static one depicted elsewhere herein). I am having a driver issue, as described in the response I just posted to David (https://i.imgur.com/yViwcTJ.png). I have a Win10H x64 box. Any input you may be able to offer will be much appreciated. Thank you.



      • Unfortunately I don’t have a Win10 to test, but the device is based on ST microcontroller, you have to search an ST driver for usb..


  2. New firmware available from automatically/network update:

    2019-05-24: V6.1
    1. Upgrade the latest version of U2p support
    2. Built-in Bluetooth APP driver
    ————————————————– ————————————————– —
    2019-05-27: V6.2
    1. Fix 6.1Emarker identification problem
    ————————————————– ————————————————– —
    2019-05-27: V6.3
    1. The first version of the U2 Bluetooth app was officially launched, temporarily supporting Android phones, requiring mobile phones to support Bluetooth 4.0.
    2. 6.3 Firmware is the first firmware to be officially adapted to APP1.0
    When using the APP function, please enable the serial port function and configure the Bluetooth module with the automatic configuration special firmware.

    There is also a new program version 4.2.


    • Find the Lowest Rec Current and Background Record options in Setup Menu, then set up a lowest recording current and a timer for offline recording. It will automatically start recording when a current higher than the lowest recording current is detected.


  3. i have received the WEB- U2 today and have updated firmware to 5.6. and pc sofware is working great in English Thanks to Mutual Support and anyone who has help in this little device i am pleased 🙂 thank you again 🙂


  4. Well, I finally received a genuine WEB-U2 in the mail. It seems that none of the previous mediafire links or the WITRN website provide firmware 5.6. Does anyone have a link? Thanks in advance!


  5. Hi WITRN-C3, i thought it was the exact same as this except for it having a usb-c instead of usb-a.

    i tried to upgrade the firmware but now it no longer boots. it says wrong app. i can only start it in dfu mode.

    anyone knows where i can find the c3 firmware?


  6. Lang.ini full translated to english.
    Copy the following content and paste in the lang.ini file

    4=Not supported
    5=Latest version
    7=Not connected
    8=Welcome to WITRN_Meter
    23=The device is not connected
    24=The device is in upgrade mode
    25=Device is not operational
    26=Thread recovery failed
    29=Failed to get data
    31=Device cannot be opened
    34=This operation needs to stop the data transfer function first!
    35=For the firmware version 1.0 you need to send the equipment back to our company for upgrade. After the upgrade, the limit can be lifted and the perfect operation can be performed!
    36=Please upgrade the firmware version!
    37=This version of the software supports a minimum firmware version of
    38=Please select the firmware file!
    39=The device is not in upgrade mode!
    40=Always press the OK button to enter the upgrade mode when the device is powered on!
    41=Firmware error
    42=Firmware check is correct
    43=Start erasing firmware
    44=Firmware erase failed
    45=Start installing firmware
    46=Firmware installation failed
    47=Start verifying firmware
    48=Firmware check failed
    49=Firmware verification succeeded
    50=Firmware installed successfully
    51=The device has entered the data transfer mode
    52=Device failed to enter data transfer mode
    53=The device has exited the data transfer mode
    54=Device exits data transfer mode failed
    60=Offline record is empty
    61=Data has been saved to
    62=Failed to save data
    63=Full screen
    64=Custom boot LOGO
    65=Allowable color difference
    66=The selected picture must be a 24-bit 128*128 bmp file
    70=Out of space
    71=Networking failed to check
    72=The best allowable color difference has been calculated automatically
    73=This image cannot be adjusted to the space tolerance
    74=Get more products
    75=The upgrade file does not match the current device!
    76=Unknown device!
    77=Save data
    79=Networking failed to get upgrade files!
    80=Networking to get files…
    81=Networking upgrade
    82=The current firmware is already the latest version
    83=Local upgrade


  7. Firmware version 5.6 was released (Release note translated whit google):
    2019-03-21: V5.6
    1. Optimize the built-in load resistance judgment condition to prevent the forced input high voltage from damaging the power resistor
    2. Due to the large heat generated during the built-in load operation, the new version of the resistor is replaced with a higher power alloy resistor to improve power and prevent heat distortion.
    3.V2.0 version PCB Modify the built-in load position and move to the center of the board to reduce the risk of fever and burns


  8. PC software 4.0 is available, same link as 3.0:
    The new software version requires firmware 5.5 to connect, so don’t try to use it if you have a fake U2!
    Lang.ini has a few new strings, the English translations are easy to obtain with Google Translate.
    My U2 is genuine, firmware 5.5 introduces a new line in the auto-detection screen listing the PD modes. With older firmware you had to enter the trigger mode to see the modes.


  9. Firmware version 5.5 was released (Release note translated whit google):
    1. Optimize the automatic detection interface UI
    2. Reserve Bluetooth APP upgrade interface


  10. Firmware version 5.4 is out on the same link with following changes:

    2019-01-30: V5.4 (New Year’s Edition, I wish you a Happy New Year)
    1. Optimize Emark detection
    2. Amend some typos
    3. Improve the MFI test process


  11. Official software support:

    U2 Manual:http://www.witrn.com/witrn/u2/WEB-U2_userguide.pdf

    U2 PC Software v2.3:http://www.witrn.com/witrn/u2/U2X上位机和升级软件V22SP3.rar

    U2 Firmware v5.2:http://www.witrn.com/witrn/u2/U2_固件.zip


  12. Here is changelog ytanslated by Google:
    2018-9-6: V3.4
    1. Optimize PD protocol to improve PD direct charge mobile phone compatibility
    2. Optimize other details
    2018-9-18: V3.6
    1. Optimized for automatic detection and identification of Kunxing PPS charging head
    2. Fix the PD sniffing interface into the voltage constant bug
    2018-10-09: V4.0
    1. Optimize the identification of the latest PPS headers
    2. Optimization Q4+ new head recognition logic
    3. Adjust the SAMSUNG 5V 2A test standard


  13. Hi, tank’s for your work and your help (sorry for my english…)
    On amazon spec, he have wifi “802.11abg” and bluetooh logo on his back, how to use it ?



    • Hello Jimmy,

      Nope, there is no wifi nor bluetooth available on this meter so far. It’s just a PCB without a wifi or bluetooth module. Bluetooth connectivity will appear in a future firmware upgrade, but you will need to purchase their bluetooth module.

      Hope this answers your question.


  14. Thanks again Magicmeter! With the lang.ini we have the U2Meter.exe in ENGLISH!!! Fantastick guys! We can make some of the Chinese products a decent product! I wish they have done this on their own! But thanks to you all supporters, I have mine on version V3.3 and in English!


  15. Hello,
    firstly I want thanks for nice videos.
    I order this meter via Taobaoring and they said that they will get firmware and software from seller but they didn’t sent it to me for longer then month. Do you know from where I can get new firmware and software?
    Also there is bluetooth but I cant see for what it used as I think only cable is used to connecting to PC.


    • I got everything from my seller. I will give you a link to the package I received.

      Yes, only cable connection is available so far. Bluetooth connectivity will appear in a future firmware upgrade, but you will need to purchase their bluetooth module.


  16. Great details and nice documentation! Do you know if this unit can be programmed? If yes, how is it done? I just purchased one but it came with a very old version and lots of chinese characters, so I’m not happy with it. Do you know, or someone who does know how to update the firmware? Thanks! Tony PS: Sorry, do not have a website so I uploaded a very bad video to youtube – that is what put in its place.


    • Hello Tony,

      Q. Do you know if this unit can be programmed?
      A. The WEB- U2 can be programmed, but only the developer can do this. It is not open source.

      Q. Are all of these devices just the exact same copies under many names?
      A. Nope, they are different. Different brands and different developers.

      Q. I’m sure they all can use the same firmware – or am I wrong?
      A. Since these devices are different, they cannot use the same firmware.

      Q. Do you know, or someone who does know how to update the firmware?
      A. Please contact the seller first. S/He should provide you with the software package and instructions.

      How to Change the System Language on WEB- U2

      1. Press and hold the M button and then connect U2 to a power supply.
      2. Release the M button when you see the setting menu.
      3. The 01 option is used to set the language, so long-press the M button to enter.
      4. Select a language you want, and then long-press the M button to save.
      5. Finally long-press the OK button to exit.

      Hope this answers your questions.


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