CanViewer

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Decoding frames ​

Every message page has a Decode frame card. Enter the bytes of a frame as you see them in a trace or a bus monitor, and CanViewer shows each signal's physical value.

EngineData decoded from E0 2E 82 3C 90 81 0C 01: 3000 rpm, 90 degC, 24 %EngineData decoded from E0 2E 82 3C 90 81 0C 01: 3000 rpm, 90 degC, 24 %

Entering bytes ​

  • Write the bytes in hex, in the order they are on the bus: E0 2E 82 3C, 0xE0,0x2E and E02E823C all mean the same.
  • Every byte needs both digits. Input that is not whole hex bytes is marked invalid.
  • Fewer bytes than the message's DLC are padded with zeros; bytes beyond the DLC are ignored. The card echoes the bytes it used when they differ from what you typed.
  • An empty field decodes as all zeros.
  • Switching to another message clears the field, so old bytes never decode into a message they do not belong to.

Reading the result ​

Each signal gets one line: its name, its physical value with unit, and the value description when the raw value has one (above, EngineRunning is 1, described as Running). Click a line to select the signal; its card then marks the matching value description.

The physical value is raw × factor + offset, with the raw value read from the signal's bits in its byte order, as unsigned or signed (two's complement) integer, or as IEEE 754 float or double for SIG_VALTYPE_ signals.

Multiplexed messages ​

A multiplexed message carries different signals depending on the value of its multiplexor. The decoder reads the multiplexor first. Signals whose switch value does not match are still decoded, but marked mux inactive. With extended multiplexing, a signal is active only when its whole chain of switches is.

The other way round, and many frames ​

  • The frame encoder does the inverse: you enter physical values, and it gives the frame's bytes. Decode in the encoder shows its frame here, and From decoder starts the encoder from the frame decoded here.
  • The Traces view decodes every frame of a log file recorded from a bus.

Limits ​

  • The decoder decodes one frame at a time, typed or pasted by you. It does not connect to a bus; for a log file, use the Traces view.
  • Decoding is plain arithmetic in your browser. Nothing is sent anywhere.