User manual

55
Serial BUS Analysis
12.7. 2 CAN BUS Triggering
After the CAN BUSconguration,itwillbepossibleto
trigger on various events. Press the TYPE button in the
TRIGGER section and choose the soft menu key SERIAL
BUSES. Then press the SOURCE button in the TRIGGER
section and choose CAN. This will only be available if
itwasconguredearlier.PresstheFILTERbuttonin
the TRIGGER section to list all available CAN trigger
conditions:
❙ START OF FRAME: Triggersontherstslopeofthe
SOF bit (synchronizing bit).
❙ END OF FRAME: Triggers on the end of the frame.
❙ FRAME: The submenu offers different options, like
trigger on ERROR (general frame error), OVERLOAD
(trigger on CAN Overload frames) or DATA (trigger on
data frames). With the soft menu key READ/DATA you
are able to trigger on read and data frames. With the soft
menukeyIPTYPEtheidentiertype(11bit,29bitor
any.) can be selected.
❙ ERROR S: Identiesvariouserrorsinaframe.Thismenu
allows you to choose one or several error message types
as trigger condition. Individual frame segments (e.g.
framestartetc.)arecodedduringthebitstufngproce-
dure. The transmitter automatically adds a complimen-
tary bit to the bit stream if it detects 5 consecutive bits
with identical value in the bit stream to be transmitted. A
“STUFF” error occurs if the 6th identical bit level is detec-
tedinthespeciedsections.AFORM error occurs if a
xedbiteldcontainsoneorseveralinvalidbits.An
authentication error occurs if the transmitter receives no
authentication (acknowledge). CAN BUS applies a com-
plex checksum calculation (Cyclic Redundancy Check).
The transmitter calculates the CRC and transmits the
result in a CRC sequence. The receiver calculates the
CRC in the same manner. A CRC error occurs if the cal-
culated result deviates from the received CRC sequence.
❙ IDENTIFIER: Identiesthepriorityandthelogical
address of a message. In the menu that opens you can
press the top soft menu key to select the FRAME TYPE
(general data, read data or read/write data) via universal
knob. The soft menu IDENTIFIER SETUP below allows
youtospecifythelengthoftheidentiertypeviasoft
menu key ID TYPE and universal knob (11 bit base or 29
bits for extended CAN frames). The soft menu key
COMPAREdenesthecomparisonfunction.Ifthepattern
includes at least one X (don’t care), it is possible to trigger
onavalueequalornotequaltothespeciedvalue.Ifthe
pattern includes only 0 or 1, it is possible to trigger on an
areagreaterthanorlessthanthespeciedvalue.The
PATTERN INPUT may be binary or hexadecimal. If you
choose the binary input, the soft menu key BIT and the
universal knob allow you to select which individual bits
within the data are to be edited. Select the option STATE
to assign a logic state to each bit (High = H = 1, Low = L
=0orX=don’tcare).ThestateXdenesanystate.If
you choose the hexadecimal input, the soft menu key
VALUE and the universal knob allow you to set the value
for the respective byte. If the input is hexadecimal, only
the entire byte can be set to X. Use the soft menu key
BYTE to toggle between bytes.
❙ IDENTIFIER AND DATA: Includes the same settings as
the soft menu IDENTIFIER. In the menu that opens you
can select the FRAME TYPE (general data or read data)
via top soft menu key and universal knob. In the menu
IDENTIFIER SETUP below you can enter the address of
the respective pattern.
❙ DATA SETUP: Allows you to specify the data bit pattern
or HEX values for up to 8 bytes (only available if DATA
was selected as frame type). Available comparisons for
address and data values are GREATER, EQUAL OR LESS,
EQUAL and NOT EQUAL.
Press the MENU OFF button several times to close all me-
nus, and the oscilloscope will trigger on the set data. For
measurements without measuring object please refer to
chapter 12.2.2.
12.8 LIN BUS
The LIN bus (Local Interconnect Network) is a simple
master/slave bus system for automotive applications and
is used for the data exchange between controller units and
sensors or actuators. The signal is transmitted on one line
Fig. 12.19: CAN BUS
For CAN BUS trigger and decoding you need the R&S®HOO12
option or the upgrade voucher R&S®HV112.
Fig. 12.18: CAN data trigger menu