Browser UI Tour¶

This page walks through the gateway's browser interface tab by tab. There are no screenshots yet — read this alongside a running gateway (scpi-web) and follow along.

Signing in¶

Before the home screen there is a Sign in panel with a single Join code field: type the six digits your lab admin read out and press Connect. An invitation link (…/?invite=…) skips this screen entirely — it redeems itself as the page loads. Automation authors, who hold an scpi_… token rather than a code, will find an I have an access token disclosure below the field. See Gateway security for where codes come from.

Home screen¶

The home screen is split into two zones: sessions already held by the server (each with an Open button to jump back in) and devices discovered on the LAN (each with a Connect button to start a session). Both zones group entries by kind — oscilloscope, power supply, or AWG — and support search. A recent-connections list remembers addresses you've used before, and a manual-connect field lets you type an IP directly if discovery doesn't find it. A mock oscilloscope, mock power supply and mock function generator are all available here too — one button per connectable instrument kind — so there's never a hardware requirement to get started with any of them.

The next section, Header, describes chrome that looks the same no matter which instrument kind is connected. The three sections after it — Canvas modes, Rail tabs, and Toolbar — describe an oscilloscope session specifically. A power supply or function generator session replaces all of it with its own panel; see Power supply session and Function generator session below.

The header spans the top of the window and looks the same no matter which instrument kind is connected: the connection status indicator, a read-only badge with a Claim button when the session belongs to someone else (the same control the home screen offers — see Home screen above), the Terminal button (see SCPI terminal below), and Disconnect, which ends the session and returns to the home screen. Because it's in the header rather than an instrument-specific toolbar, Disconnect is available for every session kind — a power supply or function generator session no longer has to be abandoned by reloading the page.

Directly under the header, an error banner appears when the session itself fails — a dropped stream, or an error frame from the instrument — carrying the detail that a red status dot alone can't show. Dismissing the banner clears the message but does not change what the status indicator reports: the connection state is the instrument's to report, not a side effect of closing a notification.

Canvas modes¶

Once connected, the main canvas toggles between three modes:

[ Time | Spectrum | Trend ]

Time — live traces. Channels are drawn as solid lines, math traces (M1/M2) and filters (F1/F2) as dashed lines, and an active reference waveform as a gray ghost trace overlaid on the live signal. The canvas receives the dense record (up to 100 000 samples per channel) and draws it as a min/max envelope, so a single-sample glitch shows as a spike instead of vanishing between drawn points. Scroll to zoom about the pointer, drag to pan, pinch on a touch screen, and double-click (or the ⟲ fit button) to fit the whole record again; the readout in the top-right shows the effective time/div and, while zoomed, the centre offset. Zooming is client-side over the record already on screen — it never asks the instrument for anything — and the window stays put as new acquisitions arrive; changing the timebase fits the view again. On a Siglent-modern instrument the trace updates once per completed acquisition, not on a fixed timer, and a full-record read itself takes about a quarter second on an SDS824X HD, so with one channel enabled at a fast timebase expect on the order of one update a second, dropping roughly in proportion as you enable more channels — at a slow timebase, slower still (a handful of seconds apart at 1 s/div is normal, not stalled), matching what the scope's own screen is doing. Other dialects have no way to ask the instrument whether a new acquisition has landed, so they poll adaptively instead.
Spectrum — a server-computed FFT of a chosen channel, with peak markers and a THD readout. If spectrum analysis is off, the canvas shows an Enable button instead of a plot.
Trend — recorded measurement series over time, one line per series with independent auto-scaling and a legend showing the latest, min, and max value for each. Before any recording has been made, this mode shows an empty state prompting you to "start one in the Log tab."

Rail tabs¶

The side rail holds one tab per feature area:

Channels — per-channel enable, V/div, offset, coupling, and probe ratio.
Horizontal — the timebase (time/div), on a 1-2-5 ladder from 1 ns/div to 10 s/div with engineering-unit display (100 µs, not 0.000100). A stepper click only ever lands on the next rung, never an arbitrary value — there's no way to nudge the instrument to a setting it wasn't designed to accept.
Trigger — mode, source, level, slope, and coupling.
Math — configure the M1/M2 expressions, e.g. C1 - C2 or INTG(C1).
Analysis — spectrum configuration (source channel, window function, dB scale) and the two filter slots F1/F2 (kind, cutoff(s), order).
Reference — save a named snapshot of a channel's current waveform, toggle Show/Hide to overlay it on the live trace, and read live correlation and max-deviation stats against the current signal.
Log — start/stop trend recording, watch a live row counter, and download the result as CSV. The measurement selection locks while a recording is active, so you can't change what's being recorded mid-run.
Measure — per-channel measurement checkboxes with live values, on every supported dialect (see SCPI Dialects for how each one is wired up).

Across the top: Run / Stop / Single / Auto acquisition controls, the canvas view-mode toggle, and CSV / JSON / Screenshot export buttons. Disconnect lives in the header, not here — see Header above, since it applies to every session kind, not just an oscilloscope's.

A CSV or JSON export on a very deep record can be refused rather than silently cut down to size — see Acquisition & export for the limit and what the error tells you to do about it.

Power supply session¶

A power supply session's panel gives every output a voltage setpoint, a current-limit setpoint, and an on/off switch, one group box per output. A readout strip above the panel shows what the supply actually reports — measured voltage, current, and power for each output, and whether it's live — which is not the same as the setpoints just entered: the readout reflects the instrument's own measurement, not an echo of what was sent. A setpoint the supply won't answer shows as --.--, and an output whose on/off state it won't report (an SPD3303X's CH3 has no output-state query at all) shows as unknown rather than a confident off.

Function generator session¶

A function generator session's panel gives every channel a waveform picker (sine, square, ramp, pulse, noise, arbitrary, or DC), and setpoints for frequency, amplitude, offset, and phase, plus an on/off switch — one group box per channel. Duty cycle appears only when that channel's waveform is a pulse, and symmetry only when it's a ramp; neither field appears for any other waveform. One "All outputs off" button below the channels kills every output in a single request, rather than one click per channel.

Above the panel, a readout strip shows one card per channel with what the generator reports back, including channels that are currently off — for a source, "is this output driving my circuit?" is exactly what the strip answers. These are read-back values, not echoes of the setpoints: an AWG clamps amplitude against its load setting and snaps frequency to its resolution, so the reading can differ from what was asked for. A value the generator won't answer shows as --.--, and a channel whose on/off state it won't report shows as unknown rather than a confident off.

SCPI terminal¶

The console for sending raw SCPI commands is no longer a rail tab — it lives in a Terminal button in the header, next to the connection status. Click it to open a full-width drawer below the rest of the session (Escape closes it too); a trailing ? sends your command as a query and shows the response, anything else is a bare write. Because it lives in the header rather than the scope's rail, it is available for every connected instrument kind, not just a scope — a power supply session gets the same drawer for anything its panel doesn't expose.

Multi-tab behavior¶

The server is the single source of truth for a session. Open the same session in two browser tabs (or two different browsers) and they stay in sync: acquisition state, the measurement selection, the active reference overlay, and trend-recording status all update live across every connected tab.