CANedge2 Docs, Release FW 01.04.02
0.4.2.2 Configuration explained
This section contains additional information and examples.
File split
File splitting can be based on file size or file size and time:
• split_time_period = 0: Split based on size only
• split_time_period > 0: Split based on both size and time - whichever is reached first
Limits
The file system limits should be considered when configuring the split size and time:
• SD-card size
• Max 1024 sessions
• Max 256 splits (log files) in each session
Above limits result in a maximum of 1024*256=262144 log files if fully utilised.
If the session count limit is reached, the logger will either:
• Stop logging if cyclic logging is disabled
1
• Delete the oldest session if cyclic logging is enabled
If SD-card becomes full (no more space), the logger will either:
• Stop logging if cyclic logging is disabled
1
• Delete the oldest split file from the oldest session if cyclic logging is enabled
Compression
Log files can be compressed on the device during logging using a variant of the LZSS algorithm based on
heatshrink. Compressed files will have *.MFC as file extension. A high window size improves compression
rates, but may cause message loss on very busy networks.
The table below lists results for J1939 and OBD data with different window size configurations
3
:
Window size (Bits) Data J1939 % (range) OBD % (range)
8 49.7 (47.1-51.4) 32.0 (30.3-32.8)
9 49.5 (46.3-51.6) 30.2 (29.6-31.1)
10 41.4 (38.9-45.5) 30.0 (29.6-30.8)
Decompression can be done using an implementation of LZSS or via the CANedge tools (see the CANedge
Intro).
Note: The split size set in split_size considers the size of the compressed data. I.e. if the split size
is 10 MB, the resulting file sizes become 10 MB regardless if compression is used or not.
1
If files are offloaded through WiFi in the case of the CANedge2, the logging will resume
3
Compressed size in percentage of original. Lower is better.
18 CONTENTS
To Next Page
Loading...