USB Autoscope Lite – Operation Manual
4. Preparing the device for use
The device connects to a laptop or PC's USB port using a USB 2.0 A/B interface cable.
The computer must have Microsoft Windows XP SP2 or higher operating system and have
the USB Oscilloscope software installed.
Before the measurements, the black alligator clip from the USB
Autoscope
Lite's ground
cord must be connected to vehicle ground on the diagnosed vehicle. The preferred
connection point is a vehicle body ground on the diagnosed vehicle. If an older vehicle,
use the engine ground. The signal measurements on the analog inputs are relative to vehicle
ground, because the vehicle ground is connected to the common ground of the device
through the black alligator clip of the ground cord.
Note that in some cases signal ground and ground of vehicle body are not at the same
potential. One example would be Lambda or Oxygen sensor ground on GM vehicles. This
can skew voltage readings if not taken in to account. In such cases a differential mode can be
used, connect one channel to the signal and another channel to the signal ground.
The device and it's cables must be placed as far as possible from the high voltage wires
of the ignition system, the exhaust manifold, and the cooling system fan.
The computer itself must be grounded using a separate multi stranded copper wire
with a cross section of more than 0.5 mm
2
, otherwise a failure of the computer or device
is possible. If a laptop running on its internal battery and with the main power supply
disconnected is used, this requirement is unnecessary.
In order to avoid distortion and / or damage to the data that are sent via the USB interface,
due to electromagnetic interference from the vehicle's ignition system, it is recommended
to ground the USB Autoscope Lite using a separate multi stranded copper wire with
a cross section of more than 0.5 mm
2
.
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