Talking to a UNI-T UT8803E bench multimeter

This is an implementation of the data protocol used by the UNI-T UT8803E (or UT8803) bench multimeter.

Status

The software provides all functionality of the original vendor software (but without a GUI) plus a few things that are not available in the windows program. However, it is not feature complete, yet: There are still a few status flags that seem to exist but I haven't figured out their meaning, yet.

It has been tested successfully with a UT8803E on LINUX (Debian 12).

In a nutshell

Start logging data

./ut8803e.py log

Log to file

./ut8803e.py log > mydata.csv

Log for 30 seconds in JSON format

./ut8803e.py -f json -p 0:0:30 log

Log for 1.5 hours

./ut8803e.py -p 1:30:00 log

Get device-ID

./ut8803e.py get_ID

Toggle hold

./ut8803e.py hold

Change display brightness

./ut8803e.py brightness

Requirements

This program depends on a few Python libraries:

• pycp2110
• construct
• click

You can install them like this:

pip3 install -r requirements.txt

pycp2110 depends on pyhidapi (will be installed automatically) which in turn requires the hidapi library. You need to install that yourself according to the instructions in the link above.

For Debian, this is the way to do it:

apt install libhidapi-hidraw0

# or

apt install libhidapi-libusb0

Usage

This is a simple command line tool that takes exactly on argument and supports a few options:

Usage: ut8803e.py [OPTIONS] CMD

  Commands:

      log             start logging data

      get_ID          get instrument id

      brightness      change display brightness (3 steps)

      select          press `select` button

      range_manual    switch to next manual range

      range_auto      set auto range

      minmax          set/toggle min/max mode

      exitminmax      exit min/max mode

      rel             set relative mode

      d_val           capacitor D value

      q_val           inductance Q value

      r_val           inductance/capacitor resistance

      exit_dqr        exit DQR mode

Options:
  -p, --period TEXT       Length of logging period [HH:MM:SS]. Max period: 23:59:59
  -i, --interval INTEGER  Logging interval [s]
  -f, --format TEXT       Logging data format (csv/json/reversing)
  --full                  show value even if ERR or OL app

Most commands act the exact same way as pressing the respective button on the instrument.

Logging data is printed in to STDOUT in csv format, by default. You can also get JSON records with --format json. Finally, there is --format reversing which will log binary and hex data of the status record. This is intended for reverse engineering additional features or adding support for other models.

and can be redirected to a file using the facilities of your operation system or shell. E.g. ut8803e/py log > data.csv on LINUX.

Warnings and Debugging information are printed to STDERR.

Protocol reverse engineering

If you are interested in how I went about figuring out the communication protocol, have a look at my blog post covering that. Sorry – only in German right now.

Contributing

If you are interested to contribute, please open an issue that clearly describes the change, feature or bugfix that you would like to suggest. If you want to implement or fix something yourself, you can submit a pull-request that addresses your issue. It makes sense to first discuss the issue before you get to work with coding. Please open a new branch for your pull request – do not use main.

The UNI-T programming manual suggests that there are at least two more status flags that haven't been implemented, yet and that I do not understand:

• Series/Parallel (SER/PAL/) in capacity and inductance mode. There are corresponding indicators on the LCD but I have no idea what that means.
• Over/underflow – again not sure what exactly that is supposed to be.

So if you know anything about that – get in touch.

The UNI-T documentation suggests that, with some modifications, this may work with other models, too:

• UT8802/UT8802N
• UT632/UT632N
• UT803/UT803N
• UT804/UT804N

Unfortunately, I do not have access to any of those models so I may be wrong. If you have one of them and are willing to help, please get in touch.