There are several places in Virtual Points where you enter an expression as part of your configuration.

Whenever you are asked to enter an expression, you can use the:

	Point and Operation selections located to the right of an Expression field.
	Edit Expression dialog box.
	Expression operations categories.
	Expression Editor operations.

Point and Operation selections located to the right of an Expression field.

1. Click the Popup Menu button to the right of an Expression field in a virtual Point Properties dialog box.

The Popup menu does the following.

Opens: The Select a Point browser. The Point Properties dialog box for a selected point. A New Point dialog box. The Expression Editor. Displays extended menus with the expression operations that are associated with the selected category.

2. Double click an operation to select it.

The operation is put at the current cursor position in the input box. If the operation requires an argument, the cursor is positioned for you to type the argument.

3. Insert a Point ID or variable either after the operator or between parentheses, if they appear with an operator.

Guidelines

A point based expression is can be up to 300 characters long.

When you use a device Point ID in the Expression Editor for virtual points, the raw value of the point is used by default.

If you want to use the engineering units value, enter EU_CONV(<point_id>) in the expression.

Edit Expression dialog box

The Edit Expression dialog box provides an area to create an expression with all the operators listed for your convenience.

Click either button to the right of an Expression field to open the Edit Expression dialog box.

	Opens the Expression Editor.
	Displays a Popup menu. Select Edit Expression to open the Expression Editor.

The Edit Expression dialog box does the following.

Button	Description
OK	Closes the Expression Editor and enters the saved expression in the Expression field.
Cancel	Cancels the expression session and closes the Expression Editor
	If the Expression field:	Then the Expression field:
	Was blank.	Remains blank.
	Had an expression.	That expression remains.
Help	Opens help.
Point Id's...	Opens the Select a Point browser.
Edit Point	Opens the Point Properties dialog box for a selected point in the expression box.
New Point	Opens a New Point dialog box.
Expression operations

Expression operations categories

Operations are divided into the following category:

	Alarm functions.
	Arithmetic.
	Bitwise.
	Conversion.
	Logical.
	Relational.
	Scientific.

More information

Point Technical Reference.

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