# Value/Optional Expression

A write connection. Assign a tag to this connection. When the operator presses the Enter key, the application writes the numeric value to the tag’s data source.

The Optional Expression connection is an optional write connection that works with the Value connection. To use it, assign a write expression to the Optional Expression connection.

The application calculates the value of the expression and writes the result to the Value connection. All write expressions must contain a question mark (?) as a placeholder for the value the operator enters at run time.

If the DecimalPoint property is Fixed position, and the DigitsAfterDecimalPoint property value is not 0, the decimal point is removed from the displayed value and the resulting value is used.

Tip: | If you do not assign the Value connection, at run time when the operator presses the button, the numeric pop-up does not open.

Example: Write expressions