12
IM 701430-51E
4.
Analyzing and Searching
Function
Channels Used with the CAN Bus Signal Analysis Function
CH1:
CAN signal input channel. For the procedure in connecting the probe, see
section 1, “Connecting the Probe.”
Math1: For displaying the stuff bit (see section 5, “Performing Stuff Bit Computation”)
after analysis.
Items to Be Analyzed
The frame to be analyzed are the following three types.
Remote Frame
Detects the Identifier value, CRC value, and the presence of Acknowledge.
Data Frame
Detects the Identifier value, Data value, CRC value, and the presence of
Acknowledge.
Error Frame
Detects the Identifier value
*
, Data value
*
, CRC value
*
, the presence of Acknowledge
*
,
and the error type.
The DL7200 classifies the error types into the following five types.
• Active Error:
When 6 or more successive dominant bits appear on the bus.
Error flag (6 dominant bits) output by an error active
(normal) unit and 6 or more successive dominant bits
appear in bit error and stuff error.
• Passive Error:
When 6 or more successive recessive bits appear on the bus.
Error flag (6 recessive bits) output by an error passive
(error-prone condition) unit and 6 or more successive
recessive bits appear in bit error and stuff error.
• Form Error:
When an illegal format is present in a fixed-format bit field.
Fixed format is as follows:
CRC delimiter is recessive
ACK delimiter is recessive
End of Frame is recessive
In addition, the DL7200 determines Form Error if the
following format is violated.
Reserve bit (r0 or r1) is dominant
DLC is 0 to 8
• CRC Error:
When the CRC calculated from the retrieved waveform
data and the retrieved CRC sequence value differ.
• Acknowledge Error: When the ACK slot is recessive.
*
If an error is detected in a frame, the analysis on the frame ends at that point, and the next
frame is analyzed. Therefore, the Identifier value, Data value, CRC value, and the presence
of Acknowledge after error detection are not analyzed.
CAN Bus Bit Rate
Set the sample speed of the CAN Bus.
Selectable values: 1 Mbps, 500 k, 250 k, 125 k, 83.3 k, and 33.3 k