Trend PVs

A trend window plots one or more PVs against time: their archived history from an EPICS Archiver Appliance, joined to their live values. The plot is archiveview's, so a trend in bobview works as the standalone archiveview does.

Open a trend

  • Right-click a widget (long-press on a touch screen) and pick Trend for its PV, or Trend with rule PVs for its PV and the PVs its rules read. The same menu adds them to a trend already open.
  • In a BOY screen, a button that would open a Data Browser or StripTool opens a trend of its PVs instead (see How BOY screens are translated).

Several trends may be open at once, each in its own window over the display, and they stay open as you move between displays. Layouts save them.

Give bobview an archiver

Without an archiver a trend is live only: each PV's line starts when the window opens. To see history, name the appliance's retrieval service:

bobview --archiver http://archiver.example.com:17668 DISPLAY

/retrieval is added unless the URL ends with it, and Phoebus's pbraw://host:port/retrieval form works too. The archiver is chosen in this order:

  1. --archiver URL, which is also remembered for later runs (not with --snapshot);
  2. none with --no-archiver, for this run only;
  3. the BOBVIEW_ARCHIVER environment variable (not remembered), for a site-wide default set in a launcher script or profile;
  4. the last archiver given with --archiver or picked in a trend's archiver pill, from settings.json beside the layouts.

The pill in each trend's top bar shows the archiver and whether it can be reached (green), is being checked, or cannot be reached (red). Click it to switch to another archiver, or to none; the switch applies to every trend window, and is remembered for the next run unless --archiver or BOBVIEW_ARCHIVER names another.

To try it without an appliance, run archiveview's mock archiver, which serves synthetic history for the test IOC's bl01t:SUM and a few MOCK: PVs:

cargo install archiveview-mockarchiver
archiveview-mockarchiver &
bobview --archiver http://127.0.0.1:17668

Use a trend

  • Time. The top bar's presets show the last hour, 8 hours, day or week; ⋯ takes a span such as 90m or 2 days, or two dates. Drag to pan and scroll to zoom time about the pointer. Moving into the past leaves Live; click it (or press L) to follow now again.
  • Values. Each value axis fits its data until you zoom it: drag an axis, or shift-scroll over it. PVs with different units or scales get axes of their own (up to four), on a log scale where that suits the values. Double-click the plot to reset.
  • PVs. Type in the search box to add a PV; with an archiver it also searches the archived names. The legend chips under the plot give each PV's colour, name and value: click one to hide its line, hover to pick it out, and × to remove it. Ctrl+V over the plot adds the PVs named in the clipboard.
  • Middle-click. On Linux (X11 or Wayland) a middle-click on the plot or legend adds the PVs named in the primary selection, as in the standalone archiveview: middle-click a widget in a display to select its PV name, or select names in a terminal or editor, then middle-click the trend. Channel Access, PV Access, loc:// and sim:// names are added (a sim:// one such as sim://sine(0, 10, 0.1) whole, with its arguments); a formula (= or eq://) isn't: use Trend in the widget's right-click menu. A middle-click in the search box pastes the selection there, and text selected in the search box becomes the primary selection. A note over the plot says what was added, or that the selection named no PVs (one naming more than 20 adds none). Windows and macOS have no primary selection, so there use Ctrl+V; in a snapshot a middle-click on a trend pastes nothing.
  • Undo. ↶ and ↷ (or Ctrl+Z and Ctrl+Shift+Z) undo and redo changes to the plot.
  • Hover over the plot for a readout of every PV at that time.

Limits

  • A PV the archiver doesn't hold is plotted live only, and its chip says so.
  • Waveforms are not plotted: their chip shows the latest array.
  • In the browser build trends are live only: a browser can't reach the archiver, and a middle-click pastes nothing: use Ctrl+V.