Choose Data Collection from the Data
menu to set up Selected Events mode. In Selected Events mode, you
determine which data values are collected by clicking 
on the
toolbar (or choosing Keep from the Experiment
menu) when a desired value is reached. When you start collection, the
current reading is shown as a point symbol moving across the graph
window. The point symbol color and shape can be changed in the Column Options
dialog.
Check Use Time Column to use the elapsed time for the X values.
If you elect not to use the time column, you can create your own. Enter the Column Name, Short Name (used when the space is too small for the Column Name), and Units. You can include special symbols (including subscripts and superscripts) in the entries using the drop-down menu. Each time you click Keep during data collection, the X column value is increased by 1.
If you check Use 10 s Average, Logger Pro will collect data for 10 seconds after Keep is clicked, and then display the average reading over that time period. This can be helpful when data values are not completely stable.