You can easily reverse the reporting direction of the Goniometer (GNM-BTA) using the data-collection software. This is very useful for comparing joint activity from left and right limbs. The instructions for reversing direction are dependent on the data-collection interface you are using.
Computer Users: Choose Set Up Sensors from the Experiment menu, then select your interface (LabQuest, LabPro, etc.). Click the image representing the Goniometer, choose Reverse Direction, then close the dialog box.
LabQuest Users: Tap the angle reading in the meter tab. Choose Reverse Direction and select the box for the Goniometer.