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Functional Description
148
4-Channel SPO Digital Oscilloscopes
X - DECODE CAN Serial Bus Decode
(cont‟d)
The oscilloscope displays the following CAN signals :
CAN_H
on CH1, yellow trace
CAN_L
on CH2, red trace
CAN_H-CAN_L
on CH3, blue trace
Note : We use a MX9030 (1/20) differential probe to capture the CAN_H-CAN_L
Acquisition « STOP », we expand the horizontal scale to 2µs/div to view the CAN datas around
the trigger event (ID 0x0108) the horizontal trigger position is indicated by the symbol
:
In « STOP » we expand the horizontal scale to view the CAN frame details and to measure with
cursors a bit width for a CAN HS (High Speed) 500kb/s :
We measure :
ΔT=X1-X2=2µs and 1/ΔT=500kb/s
We can also measure the amplitude of the CAN_H HS and CAN_L HS (
CAN High Speed
signals
) :
The CAN_H HS varies from 2.5V to 3.76V, its amplitude is :
ΔV=Y2-Y1=1.26V
The CAN_L HS varies from 2.5V to 1.40V, its amplitude is:
ΔV=Y2-Y1=1.10V