Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
4
3000 X-Series Oscilloscopes Advanced Training Guide
101
Your scope should now be triggering on LIN frame = 21
HEX
as shown in
. With this scope’s very fast hardware- based decoding, you
should also see that the frame ID field (left- most decoded byte) is
sometimes displayed in red. This is an indication that the scope is
capturing and quickly decoding infrequent parity bit errors. If the scope
detects a checksum error, the last byte in the serial string (checksum byte)
will be displayed in red. Note that Frame ID = 12
HEX
contains an
occasional checksum error. If you change to the trigger condition to trigger
on ID = 0x12, you can observe this particular type of error. Let’s now
capture a very long stream of LIN traffic (2 seconds of acquisition time)
and then manually search through the captured and decoded record.
17
Press the
[Serial]
front panel key.
18
Press the
Lister
softkey; then turn the Entry knob to select
Serial 1 (LIN)
.
19
Set the scope’s timebase to
200.00 ms/div
.
20
Press
[Run/Stop]
to stop repetitive acquisitions.
21
Press the
Scroll Lister
softkey; then turn the Entry knob to manually
scroll through the lister table.
As you scroll through the data, note that waveforms “track”. This means
that the frame that the arrow points to in the lister table corresponds to
the waveforms that are positioned at center- screen. If you want to zoom
in on a particular LIN frame of data, either push the Entry knob, or press
the
Zoom to Selection
softkey. Looking for infrequent errors in this long
Figure 75 While triggering on LIN frame = 21
HEX
, the scope’s hardware-based decoding
reveals parity bit errors in the frame ID field.