Vernier EasyData Guidebook - Manual (Page 28)

EasyData Guidebook 27
Using Photogates
When a photogate is attached, there are four photogate data collection modes that
can be used. These data-collection modes are only available when a photogate is
set up. Photogates cannot be used in conjunction with any other sensors and must
be connected to the digital (DIG) channels of the LabPro or CBL 2. When using an
older photogate, it may not auto-ID and it will be necessary to set up your
photogate manually.
Once the photogate is set up, the gate status will be displayed in the meter on the
main screen. To test the photogate, block it with your hand; the status should
report as Blocked. Once you remove your hand, it should change to Unblocked.
The default mode is Motion Timing. This mode is appropriate for a picket fence
experiment, a smart pulley, or a user-defined device. Only auto-ID photogates may
be daisy-chained. During operation, times are recorded as leading opaque edges
of a device pass through the photogate beam. These times are used to calculate
distance, velocity and acceleration.
In Gate Timing mode, the time during which one or two photogates are blocked is
measured. Corresponding velocities will be calculated from the measured times
and the width of the object used to block the gate.
In Pulse Timing mode, the time between two blocking events is measured and
stored. If you are using one photogate, the timing starts when the photogate is first
blocked, and it stops when the photogate is blocked again. When two photogates
are used, the timing starts when the first photogate is blocked, and stops when the
second gate is blocked.
In Pendulum Timing mode, the period of an object as it oscillates through the
photogate will be measured.