Expression Editor

Overview

The Expression Editor is a custom Perspective component that provides an enhanced interface for creating and editing Ignition expressions. It lets users bind an expression field to a PLC tag and transform its value with calculations using the Ignition Expression Language, with syntax highlighting, tag insertion, a live evaluated result, and error checking. It is used throughout Tamaki MES wherever a value can be driven by a tag or expression - for example the state, mode, downtime-reason, count, and rate expressions on the OEE Configuration screen.

Interface

• Text entry area - where the expression is typed. It can be populated automatically by the Browse Tags button, and edited freely to build more complex logic and calculations.
• Result line - shows the live evaluated result of the expression, or an error if it is invalid.
• Toolbar (to the right of the editor):

  • Operators Button (+=) - opens an Operators menu (Mathematical, Logical, and Bitwise) whose entries are inserted into the text entry area at the cursor:

    

  • Formulas Button (Σ) - opens a Formulas menu of built-in functions grouped by category (Advanced, Aggregates, Alarming, Colors, Date and Time, JSON, Logic, Math, Strings, Translation, Type Casting, Users):

    

  • Browse Tags Button - opens the Browse Tags modal to select a PLC tag to insert:

    1. The top dropdown selects the tag provider; the tree below navigates the tags in that provider.
    2. To insert a tag, select it and click Confirm, or double-click it.

    

Example: bind an expression field to a PLC tag

1. Click the Browse Tags button on the right of the expression field.
2. In the Browse Tags modal, navigate to the desired tag (for example a location's mode or state tag) and select it.
3. Click Confirm to insert the tag path into the editor. The Result line updates to show the tag's live value, confirming the binding.

Props

The Expression Editor component has the following props:

Prop Name	Type	Description	Input/Output
expression	string	The current Expression.	Both
isValid	boolean	Indicates whether the current expression is valid.	Output
showOperatorsButton	boolean	If true, shows a button to insert operators into the expression.	Input
showFunctionsButton	boolean	If true, shows a button to insert functions into the expression.	Input
showTagBrowserButton	boolean	If true, shows a button to insert tags into the expression.	Input
cursorIndex	number	The current cursor index in the expression.	Output
expressionResult	any	The result of the expression, if it is valid.	Output

Events

The Expression Editor component emits the following events:

Event Name	Description	Payload
onOpenTagBrowser	Emitted when the user clicks the "Insert Tag" button.	None

Notes

• The Expression Editor is designed to be used in conjunction with the TamakiMES/_components/ExpressionInput Perspective View, which provides a complete interface for editing expressions, including a label, description, and error messages.
• For expression syntax, refer to the Ignition Expression Language documentation.