On the toolbar on the left, click the Sensors tab.

On the Sensors pane, click the Variable Sensor button.

In the Variable Table dialog box, click the row button for the variable you want to track as a sensor.

In the Variable Sensor Parameters dialog box, click the Add Variable button.

In the Variable Sensor Parameters dialog box, define the sensor parameters, and then click OK.

The sensor is displayed on the Sensors pane.