Work with value axes

You never have to set up a value axis: each PV picks one when its data first arrives, and the axes name themselves. When the choice is not the one you want, moving a trace takes a click or two.

How a new PV picks its axis

When a PV's data arrives (its archived history, or a second of live values if it has no history), archiveview compares it with the axes already on the plot. PVs pick in the order of their chips, whatever order the archiver answers in, so a view always comes up the same way; a PV is drawn once it has picked.

  • Units first. A PV never joins an axis whose traces have other units: a beam current in mA and a lifetime in h get an axis each. This holds however many axes there are.
  • Then size. With the same units (or none), it joins an axis whose values are within about a factor of ten of its own, a little more when their ranges overlap. SA:X and SA:Y of a BPM, both in mm, share an axis; a current of 300 mA and one of 0.3 mA do not.
  • States apart. An enum or binary PV gets an axis of its own, named after it, with ticks at whole numbers. Only enums with the same states share one ("State").
  • Log scale. A pressure, or a PV whose values span several decades, gets an axis on a log scale.
  • About four axes. Past four axes of values, a new PV joins the closest axis with its units even when the sizes differ; with none, it still gets its own.

The choice is made once. Zooming, panning and reloading never move a trace to another axis; only you do.

The axes alternate sides: the first on the left, the second on the right, then a third left of the first and a fourth right of the second. The first chip's axis is always the first.

Move a trace to another axis

  • Click the colour dot on its chip for a menu of the axes, and New axis.
  • Or drag the chip onto an axis. Drop it anywhere else on the plot to give it an axis of its own.

An axis that loses its last trace disappears.

Pick out an axis' traces

Click an axis (its labels or name) to show its traces in full and dim the others. Click it again to show them all.

Zoom one axis

With the pointer over an axis, drag up or down or shift-scroll to zoom that axis alone. Over the data, shift-scroll zooms every axis about the pointer. ⤢ or A autoscales them all again.

Names

An axis names itself from its traces:

  1. the quantity from the units, such as Current (mA), Position (mm), Time (h); unknown units show as they are, (counts);
  2. when two axes have the same units, the part of the PV names that tells them apart: Position X (mm) and Position Y (mm);
  3. without units, the PV's description, when the archiver gives one;
  4. otherwise Axis 1, Axis 2, ...

An axis of states is named after its PV, or State when several share it.

Hover a name to read it in full, with its units and its traces. Double-click a name to type your own; Enter keeps it, Esc does not. Clear it to go back to the automatic name.

An axis with one trace shows its name in the trace's colour. One with several shows a small dot in each trace's colour by its name.

Log scale

Right-click an axis for its own menu: Log scale, Autoscale and Rename…. ≡ ▸ Log scale turns the log scale on or off for every axis.

Everything here (which trace is on which axis, each axis' zoom, log scale and name) is saved with the view.