A universal CAN bus monitoring program
A gui-program for Windows and Linux which is ideally suited for looking at the data on unknown CAN buses and for making sense of it and decoding it.
The aim is to support as many different CAN-adapters as possible and to make the program easy to use and yet powerfull.
As of now, the following adapters are supported:
- SLCAN (used in a lot of hobby project CAN adapters, but also in some commercial ones)
- Lawicel CAN232
- Lawicel CANUSB
- USBtin (by Thomas Fischl)
- probably lots of others
- China - these can be found on ebay when searching the term "USB CAN" for about 18 dollars.
Sadly, there is no manufacturer name or device name given. They say "USB CAN Analyzer V7.1"
or something similar on the case. These mostly work, but the sadly the adapters themself are
a little buggy, and loose messages once in a while. Don't use if this is a problem for you.
- Tritium Ethernet-CAN-bridge - these are quite nice but pretty obscure. They are sold by the Australian company Tritium to be used with their solar car products. We use these regularly at the Bochum Solar Car team.
- PCAN - supports different adapters from the German company PEAK System. These adapters are very nice, but also expensive. The support in CAN Monitor 3000 is still work in progress. As of now it is only tested with Windows and PCAN-USB. To use this adapter you need to install it's Windows-driver and PCAN-Basic from PEAK Sytem's website.
You can type format strings into the field "Format String" to decode the data of the CAN message.
The format string consists of up to 8 fields seperated by a comma (",") that have the following format:
TYPE [MULTIPLIER][:[TEXT][[0].NUM_DIGITS][TEXT]]
| specifier | description |
|---|---|
| u8 or U8 | unsigned 8 bits |
| u16 | unsigned 16 bits little endian |
| u32 | unsigned 32 bits little endian |
| s8 or S8 | signed 8 bits |
| s16 | signed 16 bits little endian |
| s32 | signed 32 bits little endian |
| U16 | unsigned 16 bits big endian |
| U32 | unsigned 32 bits big endian |
| S16 | signed 16 bits big endian |
| S32 | signed 32 bits big endian |
| f | floating point 32 bits little endian (IEE754 single precision) |
Consider a CAN message with the data bytes 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 decoded by the format string "u8,u8,u16,U32".
The first two bytes will be decoded by the two "u8" type specifiers and give "1,2".
The next two bytes will be decoded by the "u16" type specifier and give 3*1 + 4*256 = 1027 (little edian)
The next(last) 4 bytes will be decoded by the "U32" type specifier and give 5*1677216 + 6*65536 + 7*256 + 8 = 84281096
So the complete decoded message will be "1, 2, 1027, 84281096"
Consider a CAN message with the data bytes 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 decoded by the format string "u8 10:Foo=0.1V,u8:Bar=0.0A,u16 0.05,U32 0.001:Blub is 0.2 squiggles".
The raw numbers are going to be the same as in the example above, so I won't explain them again.
The first byte is going to be decoded by "u8 10:Foo=0.1V". This will multiply the raw value of 1 with the multiplier of 10, and then display it with the free form text after the colon and 1 place behind the decimal point. This gives "Foo=10.0V".
The second byte is going to be decoded by "u8:Bar=0.0A". This uses only the free form text with zero places after the decimal point, so it gives "Bar=2A".
The third and fourth byte are going to be decoded by "u16 0.05". This only uses the multiplier of 0.05 on the raw value of 1027, which gives "51.35". The number of decimal places (2) is deduced by the number of decimal places in the multiplier if no explicit number of decimal places is given in the format string. In the case of the "f" type specifier (not used here) 2 decimal places is the default.
The fourth to eighth byte will be decoded by "U32 0.001:Blub is 0.2 squiggles". Here the raw number of 84281096 is going to be multiplied by 0.001 and then rounded to 2 decimal places and put in the free form text. This gives "Blub is 84281.10 squiggles".
So the complete decoded string will be "Foo=10.0V, Bar=2A, 51.35, Blub is 84281.10 squiggles".