2-27
IM 701450-51E
CAN Bus Signal Analysis Function
2
Explanation
Setting the Analysis Conditions: Analyze Setup
You can set the following conditions.
Channels Used
Select CH1 or CH3 for the CAN Bus signal input channel.
In addition, Math1 is used to display the results of stuff bit computation.
Items to Be Analyzed
The frames 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.
*
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.
The DL7440/DL7480 classifies the error types into the following five types.
• Active Error
• When 6 or more successive dominant (logical value of 0) 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 (logical value of 1) 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.
• When a violation occurs in one of the following formats.
• When the reserve bit (r0 or r1) is dominant
• When DLC is between 0 and 8
*
The following three fixed formats are available.
•
CRC delimiter is recessive
•
ACK delimiter is recessive
•
End of Frame is recessive
• 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.
2.5 Analyzing/Searching Data