# Overview

The CSS EPICS PV Tree displays the hierarchical data flow between EPICS records. It displays the record types, their current values as well as severity/status. It attempts to follow the data flow by traversing input links (INP, INPA, DOL, ...).

## Usage

Enter a name into the "PV" text box, and see what happens. Names can be entered in various ways:

- Type a PV name (Autocomplete will help you), followed by "Return".
- Select a previously entered PV name from the drop-down list attached to the PV name text box.
- Drop a PV name from another CSS application into the "Tree" area below the PV name.
- Send a PV name to the EPICS PV tree via the context menu of another CSS application.

## Examples

The first screen-shot shows an analog input (ai) record, which reads its input (INP) directly from a device support module that happens to understand the input description "adm606m....".

The second screen-shot shows a more interesting hierarchy: A binary input record (bi) reads from a calculation (calc), whose first input (INPA) reads from an mbbi which in turn reads from another calc and so on. Note how the color-coding indicates severities.

## Tool Bar Buttons

- Collapse the tree, i.e. close all sub-sections of the tree.

- Display all items in the tree that are in an alarm state. Note that this is performed whenever you push the tool bar button. If the PV tree items update, branches will not automatically show or hide based on their alarm state, because this could result in a very nervous display for a rapidly changing PV tree. Whenever you desire to update the tree to show/hide items, push the button.

- Expand all sub-sections of the tree.

## Limitations

This tool uses the EPICS network protocol, Channel Access, to read PVs. There is no way to query EPICS V3 IOCs for their database information to determine the available "input" links.

The knowledge of which links to follow for each record type is therefore configured into the EPICS PV Tree application. It is at this time not configurable by end users, but people with access to the source code can determine the syntax from the preferences.ini file and override in the CSS plugin_customization.ini for site-specific settings.