The webapp

The webapp runs in your browser and talks only to central NATS, over WebSocket. It lists the LabJack configurations in the central avenabox bucket, edits them, plots live channels, and downloads archived data as CSV. It never connects to an edge node directly, so it works from anywhere on the Tailscale network.

Run it

You need Node.js 18 or newer and pnpm.

cd avena-rs/webapp
corepack enable        # provides pnpm, if it is not installed already
pnpm install
pnpm dev

Open the address Vite prints, normally http://localhost:5173.

Connect

On the first page, enter the central WebSocket address and choose a credentials file:

The address and credentials are kept in the tab’s session storage until you log out or close the tab, and are only used to connect to NATS.

Plot a box

The LabJack page lists every configuration in avenabox, one per edge node. The Enabled or Disabled badge on each card is the configuration’s labjack_on_off setting, not a live status. Opening one shows its live channels. Asset numbers are not guaranteed to be unique between boxes, so the plot address carries the configuration key:

/labjacks/plots/1001?key=i69.i69-mu1.i69-lj2.config

The plot page shows up to two channels at a time and receives only the ones you select, so selecting a channel again starts an empty plot. Each channel says whether it shows raw volts or calibrated values and in which unit; a calibrated channel also shows its latest raw reading in volts. The unit is the one set with the channel’s calibration in the configuration form; if a channel says “unit not set”, edit the configuration and choose it. A channel with noise filters in its configuration is drawn filtered, with a FILTERED badge; its Filtered / Raw switch shows the unfiltered values instead, without saving anything.

The connection badge reads Connecting, Connected, Reconnecting or Disconnected. When the connection drops, a banner says the page is reconnecting, and the plots carry on by themselves afterwards with a gap for the missing time. If a plot stays empty, check on the command line that samples are arriving at central NATS:

nats --server nats://nats1.oats:4222 --creds apt.creds \
  sub 'avenars.i69.i69-mu1.i69-lj2.live.>' --count 3

Change what a box records

Editing a configuration in the webapp writes the central key. The box’s streamer mirrors the change within a moment and, if the channels, rates or identity changed, restarts sampling with the new settings; the archiver starts a new file when a channel’s calibration changes. Each channel has one calibration, set in the form together with its unit (for example kPa for pressure or µε for a strain gauge); a strain gauge’s calibration can be worked out from its certificate factor, the bridge excitation and the amplifier gain with the form’s bridge helper. Each channel can also have noise filters (spike removal, 10 Hz and 11.9 Hz removal, high- and low-pass); they change only what the plots and exports show, never the archive. The LabJack configuration reference explains each field, and Noise on the I-69 sensor inputs what the filters are for.

Download data

The export dialog starts with the plotted channels and the last two minutes. Times are to the second in your browser’s time zone, which the dialog names, and the same range is shown in UTC underneath. If a channel has filters, “Include filtered values” adds a filtered_value column to the CSV. In Chrome and Edge you choose where to save before the export starts, and the file is written as the data arrives; other browsers save it as a download at the end. Cancel Download stops a running export and saves nothing; the box may still send a few more chunks before it notices, for up to about 30 seconds. The request goes through central NATS to the exporter on that box, which reads its Parquet archive and streams the rows back as CSV. Large ranges take a while: the edge node’s uplink is usually the limit.

The same request can be made from the command line, which is handy for scripting and for checking the export path without a browser. See Command-line tools.

For how the webapp is put together, and how to build and host it for others, see How the webapp works and Developing and deploying.