Decoder Example

[lampenrecht]

Is the code example on the main page still up to date?
Im trying to decode some data with the code from the example, but get everytime this error:
ldf = ldfparser.LDF("MQB2020.ldf")
TypeError: init() takes 1 positional argument but 2 were given
or
ldf = ldfparser.LDF(path = "MQB2020.ldf")
TypeError: init() got an unexpected keyword argument 'path'

Could i pls get a short code for decoding?

[c4deszes]

Sorry for the inconvenience, the parsing interface has changed since, the LDF class is now a container only and the parsing is done separately.

Replacing the read step with ldf = ldfparser.parseLDF("MQB2020.ldf") should be do the trick.

I recommend checking the examples found here as they will be always up to date, because they're tested in the CI workflow.

[lampenrecht]

Thanks for your answer.

Is the decoding of raw data, like "\xc8\xd1\x00\x64\x80\x02", with a frame still possible?
I found all the decode functions for various types of variables in your code, but to be honest, im a python beginner and i dont know how to deliver the data to this functions

thanks for your help

[c4deszes]

Yes, given a frame definition you have two possibilities when decoding.

You can decode the data in a "raw" format, which means that the signals are extracted but the physical values are preserved.

ldf = ldfparser.parseLDF("MQB2020.ldf")
frame_1 = ldf.frame('Frame_1')  #Replace with a frame id or name that actually exists
data = bytearray("\xc8\xd1\x00\x64\x80\x02", 'UTF-8')

# decoded in this case is going to be a dictionary, where the keys are the signal names and
# the values are the physical values.
decoded = frame_1.parse_raw(data)

# you can access signal values using the python index operator
print(decoded["Signal_1"])

# imagine that `\x02` at the end of the frame is a 4 state signal (0: init, 1: ok, 2: not ok, 3: error), in this
# mode the returned value is going to be 2

You can also decode the data through the signal encoders defined in the LDF file, so if there's for example a mapping in the LDF to interpret a bits or integers in a certain way then they're going to be converted accordingly. The method is similar except you have to pass a converter set, when you have signal encoders specified in the LDF then you can use them using the following snippet:

decoded = frame_1.parse(data, ldf.converters)

print(decoded["Signal_1"])
# imagine the same scenario as above, if the signal encoders are setup correctly then
# the decoded value is going to be "not ok" (2)

Hope this helps.

The code has inline documentation, so if you have working autocomplete it should be easy to understand what variables and functions you can access, but I'm working on an larger update (0.8.0) that should help in the documentation aspect.

[lampenrecht]

Thanks a lot for this snippets, now it works great ;)