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now we're going to do a demonstration
now and we'll do it on the 4000 series
we don't have time to demonstrate all of
the serial buses for automotive we're
going to focus on the can bus and we're
going to take a look at decoding can
triggering on can
and a k ni diagram
so i've already connected my probe tips
up to my differential bus let's plug the
probe into the scope
and let's set it up to decode and
trigger on the can bus so here's our
differential can bus signal let's
rescale the vertical
set my trigger level about in the middle
of the this bus
and you can see that it's a pretty
complex signal
i'm going to go into the serial menu
and these
are the various serial buses that are
supported with the ultimate bundles the
buses that are specific to automotive
are can
lin
flex-ray
scent
cxpi and manchester manchester supports
psi psi5 now automotive they also use i
square c spy and uart so they use very
many many of these so i'm going to
select can
next i'll go into the signals menu
and select the
baud rate which this particular bus is
500 kilobits per second that's the most
common high-speed baud rate for can in
automotive applications
and here you can see it decoding
let me turn on the lister this shows it
in a tabular format it still looks like
a blur of signals that's because
we're not triggering on can yet we're
just triggering
on edge crossing so i'm going to go into
the trigger menu
and change from triggering on edges
to triggering on the can bus
right now it's triggering on start of
frame
let's change it to trigger on a frame id
and there's a frame id i know is
valid
two one one hex
and there we have locked in
on one particular can bus frame so what
do all these hexadecimal codes mean well
if you were designing this system you
would probably know this is the frame id
this is data link code equals eight that
means there are eight bytes of data
following that and then there's a crc at
the end but there's a better way to view
this
these scopes both the better and best
support symbolic decoding of the can bus
so i'm going to recall
what's called a database file dbc file
database can
select
can symbolic data
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there's my file
and now it's decoding it symbolically
you can see it's triggering on
break torque in fact let me go back to
the trigger menu
instead of triggering on frame ids that
are hexadecimal numbers
you can select
to trigger on message names now they
correlate to a frame id
so now this is breaktor
now some things that are unique about
keysight's automotive solution
is that
the infiniivision oscilloscopes decode
in hardware
so you get an extremely fast decode
update rate most other scopes decode in
software
now what the
hardware based decode gives you is it
can find error conditions very quickly
we can also trigger on these error
conditions
one last demo here is an eye diagram on
the can bus
it's very easy i'm going to select save
recall
recall i'm going to recall a mask
keysight provides these masks that
customers can download
and let's recall this mask here
and the scope will automatically set
itself up
put in a pass fail mask
and it shows you this is one bit time
for 500 kilobits per second
this is the pass fail mass you can see
we have a glitch right in the middle
there we have a transition and again
mass testing
on the uh keysight oscilloscopes is
hardware based so you can see we've
already tested
150 000
bit times
no other scope can test this fast
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