User manual

GPX Pro Manual35
© 2009 XT Racing
from the list. Select Custom if you want to select one of the Generic types.
Pressing Select on an Hz entry allows you to change the sampling rate for that input.
You should not record data at a higher sample rate than you need
- higher sampling rates use up the memory more quickly in the
GPX and result in less time that can be stored before data needs
to be deleted.
Press Select on an Enabled entry allows you to change an input from enabled to disabled and vice
versa.
When you press Select on a Cal entry, you may then calibrate or uncalibrate that input. Each type
of data has a different calibration procedure.
Temperature- and switch-type inputs may have an alarm set. See the section below entitled
Alarms.
The lower portion of the screen shows the current value for the currently highlighted input, and
information about its calibration. Also, for analog channels, the approximate real-time voltage of
that input is shown. This voltage reading can be useful when trying to determine if you have
hooked up the input properly to the vehicle.
1.7.3 Typical Inputs
1.7.3.1 RPM
The GPX can record RPM data. RPM may be picked up in two different ways – either “direct” or
“coupled” (induction).
“Direct” mode requires that a signal be available on your vehicle which is a pulsed, binary logic
signal which is either generated by a Hall-effect-type pickup from a timing wheel, or is generated
by the vehicle’s engine control unit/module (ECU or ECM). Most fuel-injected engines will have
such a signal available. The signal can be as low as a 3.3-volt peak-to-peak signal, or as high as a