# Set up connections for the numeric input enable button

## To set up tags and expressions for the button

1. In the Graphics Display editor, double-click the button to open its Properties dialog box.
2. Click the Connections tab.
3. Assign a tag or expression to these controls:

   Value

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

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

   Optional Expression

   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 Decimal Point option is set to Fixed position, the Fixed position output is Stripped Value, and the Digits after decimal point option value is not 0, the decimal point is removed from the shown value and the resulting value is used.

   Tip: | If an Optional Expression is assigned, ramping is disabled.

   Enter

   A write connection. Assign a tag to this connection. This connection accepts values of 0 and 1 only. The connection determines how long the Enter key press is registered. Use this connection for Enter key handshaking.

   Enter Handshake

   A read connection. You can assign a tag or an expression to this connection. This connection resets the Enter connection, using the Handshake Reset Type option specified in the Timing tab. Use this connection for Enter key handshaking if you want the Enter connection to be reset when a value at the data source changes.

   If you assign an expression, the application calculates the value of the expression and resets the Enter connection when the expression value meets the conditions of the Handshake Reset Type.

   Minimum

   An optional read connection. If the Use variable Minimum/Maximum check box on the Numeric tab is checked, assign a tag or an expression to this connection. If the check box is not checked, this connection is not read.

   The application reads the value of the tag or expression to determine the minimum value the object can write to the data source.

   Maximum

   An optional read connection. If the Use variable Minimum/Maximum check box on the Numeric tab is checked, assign a tag or an expression to this connection. If the check box is not checked, this connection is not read.

   The application reads the value of the tag or expression to determine the maximum value the object can write to the data source.

## See also

Set up general properties for a Numeric Input Enable button

Set up numeric options for a Numeric Input Enable button

Set up handshaking for a Numeric Input Enable button

Columns on the Connections tab of a graphic object's Properties dialog box

Example: Write expressions