Datasheet

Application Note
www.tektronix.com/oscilloscopes22
The intermission (INT) field of three recessive bits indicates the
bus is free. Bus Idle time may be any arbitrary length including
zero.
A number of different data rates are defined, with 1Mb/s being
the fastest, and 5 kb/s the minimum rate. All modules must
support at least 20 kb/s. Cable length depends on the data
rate used. Normally all devices in a system transfer information
at uniform and fixed bit rates. The maximum line length can
be thousands of meters at low speeds; 40 meters at 1 Mb/s
is typical. Termination resistors are used at each end of the
cable.
Working with CAN
Several options enable CAN serial triggering and analysis
on multiple Tektronix oscilloscope families (see Appendix A).
Using the front panel Bus buttons we can define a CAN bus
by simply entering the basic parameters of the bus including
the type of CAN signal being probed and on which channel,
the bit rate, threshold and sample point (as a percent of bit
time), see Figure 30.
Imagine you need to make timing measurements associated
with the latency from when a driver presses the Passenger
Window Down switch to when the CAN module in the driver’s
door issues the command and then the time to when the
passenger window actually starts to move. By specifying
the ID of the CAN module in the driver’s door as well as the
data associated with a “roll the window down” command,
you can trigger on the exact data frame you’re looking for.
By simultaneously probing the window down switch on the
driver’s door and the motor drive in the passenger’s door this
timing measurement becomes exceptionally easy, as shown in
Figure 31.
The white triangles in the figure are marks that we’ve placed
on the waveform as reference points. These marks are added
to or removed from the display by simply pressing the Set/
Clear Mark button on the front panel of the oscilloscope.
Pressing the Previous and Next buttons on the front panel
causes the zoom window to jump from one mark to the next
making it simple to navigate between events of interest in the
acquisition.
Figure 31. Triggering on specific identifier and Data on a CAN bus and decoding all
messages in the acquisition.
Figure 30. CAN bus setup menu.