The shared vertical cursor pair and the per-row horizontal rulers, their four modes, and how a reading is formatted. Martino Ferrari Cursors

Cursors read values off the traces. There are two kinds: one shared vertical pair that every row carries at the same time, and horizontal rulers, one pair per row, that belong to that row alone.

How to reach it

Press the cursors button in the header bar, or c. It switches the cursors on and off.

The readings are in the dock (a read-only copy) and on the Cursors page, which Edit beside Cursors opens over the plot and which owns the mode and a Reset button. Drag a marker to move it.

The mode dropdown offers four modes: vertical (the shared time pair), horizontal (the per-row rulers), both, and mix.

Worth knowing

The vertical pair is one time for the whole figure, so moving it on any row moves it on all of them. That is what makes dt meaningful across rows.

A ruler belongs to its row and nothing shares it, so two rows' rulers are independent. The plots of a split row are one row here: they share their y axis, so the rulers are at the same values in each.

mix is the reading mode: one line per bound trace, with the trace's own values at each marker and their difference. A slot with a name but no channel behind it is not a trace and gets no line.

A value is the nearest stored sample's, never a number between two samples. Zoom in past the sample spacing and the line between two samples is something the plot drew, not data — so a reading off it would be the drawing. The hover crosshair reads the same way.

Every reading carries a metric prefix so the digits sit in 1..999: 10.52 mV, not 0.01 V. Two decimals is all an instrument landing on an f32 sample can claim, so without the prefix a small value would read 0.00 and the reading would be gone. A stream that declares no unit gets the prefix anyway, written tight against the number (585.24m) — the space separates the number from its unit, and a spaced m with nothing after it would read as metres.

A marker past the newest sample reads --. With only one marker over data the row reads partial: a difference between a number and nothing is not a number.

The hover crosshair also writes its two coordinates where the eye already looks: the value where its horizontal line meets the y axis, and the time where its vertical line meets the x axis — each in a small box among that axis' own tick labels, in the axis' own format. Each box is centred on the line it names, and its background covers what is behind it, so a tick label underneath never prints through the number. The preference's Crosshair axis labels turns the pair off.

In a split row the horizontal line runs across every plot of the row, not just the one under the pointer: the plots share one y range, so it is one value along the whole row. It stops at the row's edges — another row has a scale of its own.

In mix each marker also places a crossing annotation per trace, which is what lets you see on the plot which sample a number came from. It is on that sample, so when the marker falls between two it sits a little off its own line: the line is where you put the marker, the dot is the datum being quoted. The hover crosshair's mark snaps the same way, and is drawn larger than a trace's sample dots so it does not read as one more sample.

The time row exists only in the modes that show the vertical pair. horizontal has no time row, by design.

A cursor stays where you put it while a live view rolls under it, which is what a bench scope does: its T0 is an age, so a marker left at -1.5s keeps reading the sample a second and a half old as the stream advances. A measurement's marks do the opposite — they travel with the sample they measured — because a cursor is a question you asked and a mark is an answer about one particular sample.

Example

Three traces in mix mode with both markers over data: 3 lines and 6 crossing marks, each line reading like sine 0.31 V -0.84 V -1.15 V. Move the second marker past the newest sample and the third column reads --.