Use external triggers to set up hardware triggers using the logic probes. All pins (whether used or unused) should either be pulled up or grounded. Floating pins may produce false triggers.
External triggers can be used as input to halt program execution when an external event occurs. They can also be used as output to control external devices.
Open Project Properties window.
Select REAL ICE under Categories.
Select External Triggers from the Options Categories combo box
Configure the triggers you want to use.
Select the trigger you want to use and use the drop-down window to configure it as an input or output.
For an input, specify if it is positive or negative edge triggered, and whether you want to halt or reset on trigger.
For an output, specify if you want to generate a low to high or high to low pulse, and whether you want to generate it on halt or run.