Option 3.2.3. Value Accum

Select Value Accum in the Calculation field on the Virtual tab of the Point Properties dialog box.

A Value Accum point adds the current value of the source Point ID that you specify in the Expression field to the current value of the Value Accum point.

Values continue to be added until a Reset Condition is reached.

Note: A Value Accumulator point is writable, i.e. you can use the Point Control Panel or a script to set the value, overwriting the accumulated value.

1	Expression
2	Reset point
3	Trigger point

1	Expression

Enter an Expression that calculates the value of the Value Accum point.

The expression will be monitored for transitions.

The expression may contain:

One or more Point IDs along with

Constant values, operations, and functions.

Buttons to help with the equation are as follows.

Opens the Expression Editor.

Displays a Popup menu to:

Open:

The Select a Point browser.

The Point Properties dialog box for a selected point.

A New Point dialog box.

The Expression Editor.

Display an extended menu with the associated operations.

2	Reset Point

Based on whether there is an entry in the Reset Point field, at runtime the Value Accum point is reset as follows:

When the trigger point is not defined
If	And	Then
An Initial Value Accum Point Value is	The Current value of the Expression is	The Value Accum point value is reset to the:
Not defined	Unavailable	Zero
Not defined	Available	Zero
Defined	Unavailable	Initial value
Defined	Available	Initial value
When the trigger point is defined
If		Then
An Initial Value Accum Point Value is		The Value Accum point value is reset to the:
Not defined		Zero
Defined		Initial value

Note: Buttons to the right of the Reset Point and Trigger Point fields help with configuration.

Opens the Select a Point browser to select an available point.

Displays a Popup menu to:

Open:

A New Point dialog box.

The Point Properties dialog box for a selected point.

The Select a Point browser.

Select a recently selected point.

3	Trigger point

When the value of the Value Accum point updates depends on whether or not you defined the trigger point as follows:

Trigger point	The value of the Value Accum point is Updated whenever the Value of the:
Defined	Trigger point is updated.
Not defined	Source point in the Expression field is updated.

Buttons to help with the trigger point have the same functionality as the buttons to the right of the Reset Point field.

More information

Step 3.2. Configure virtual calculations.