QtEDM / docs

Appearance

Macros and dynamic behavior ​

Dynamic Attributes ​

Graphics widgets support dynamic attributes that change appearance based on PV values:

  • Visibility – Show or hide based on PV value or calculation
  • Color – Change color based on alarm state or discrete value

Macro Substitution ​

PV names can include macro references like $(P) that are replaced at runtime. This allows creating reusable displays that work with different devices.

Local Plugins and Property Rules ​

Reviewed facility plugins can add display types and CA/PVA-adjacent data or archive providers without changing the QtEDM executable. Declarative property rules provide a separate sandboxed path for display-author logic when a native plugin is unnecessary. Both mechanisms preserve unknown ADL extension data so a temporarily missing plugin does not destroy a display.

Related Display widgets can open additional displays, optionally passing macro substitutions and replacing or overlaying the current display.

Expression Channels and Soft PVs ​

QtEDM provides expression channels as a built-in local-logic feature. An expression channel evaluates an EPICS calc expression over up to four input channels and publishes the result as a named soft PV inside the QtEDM process.

  • Publish/subscribe model – Other widgets consume the result by setting their channel name to the expression channel's variable value.
  • Chaining – One expression channel can subscribe to another expression channel's output by referencing its variable name in Channel A through Channel D.
  • Startup behavior – The configured initialValue is published immediately when EXECUTE mode starts.
  • Event control – Publication can be gated by Never, On First Change, On Any Change, Trigger Zero To One, or Trigger One To Zero.
  • Scope – Soft PVs are visible within the same running QtEDM process, including across multiple open displays in that process.

Printing ​

Displays can be printed using the File > Print menu. Page setup options allow configuring paper size and orientation.

PV Information ​

Right-click on a widget in EXECUTE mode to access PV information including connection status, current value, alarm limits, and access rights.