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Thread: Reading 7+ parameters from Advanced Measurement Values menu

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    Reading 7+ parameters from Advanced Measurement Values menu

    I am trying to debug an issue with my 2016 Touareg's transmission / engine / torque convertor and I am using VCDS to log data when driving. I have been using Advanced Measurement Values option under Transmission controller block, reading data and then saving it into text file using the log command. I did notice that there seems to be a limit as to how many parameters I can interrogate at the given time and save into the log file. The manual states that up to 12 parameters can be logged at a time, but for some reason, it seems that I am capping at half of that value. When I put more than 6 parameters, all values in the screen turn into NA and nothing gets logged into the text file. I read through manual section 13-A a few times, but there are no details about such limitations.

    Any thoughts?

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    Benevolent Dictator Uwe's Avatar
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    Are you using the "Group UDS requests" feature?

    Most control modules have a limit to the number of values that can be grouped into a single request, but that limit isn't the same on all modules. Start by un-checking "Group UDS requests" entirely and see what happens. You should be able to get 12 that way, but sample rate will be slow, which is expected.

    Then enable it again and try playing with the "split" drop-down next to it. This splits the values into two requests at the number specified.

    -Uwe-
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    Thank you Uwe. When un-checking "Group UDS requests" entirely, the sampling rate drops dramatically (well below 0.5 sample per second), which obviously misses a lot of interesting data. I will try to experiment with split drop down and see how it goes.

    Is the sampling rate dependent on the laptop CPU / load?

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    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by mmmzon View Post
    Is the sampling rate dependent on the laptop CPU / load?
    Unless you're running a really old, slow machine, I wouldn't expect it to have much influence. In general, it's more a question of how quickly a control module is willing to answer requests. Without "Group UDS requests", every value is a separate request.

    -Uwe-
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    Quote Originally Posted by Uwe View Post
    Unless you're running a really old, slow machine, I wouldn't expect it to have much influence. In general, it's more a question of how quickly a control module is willing to answer requests. Without "Group UDS requests", every value is a separate request.-Uwe-
    Currently using dual core Celeron so perhaps it is a bit on a slow end, especially for Windows 10. More experimenting to take place today and I will report back, once I have a chance to use something more powerful. Thanks!

  6. #6
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    An update - with some experimentation, I was able to log 10 parameters with real time display on the screen. CPU. hard drive, etc., do not seem to have much to do with the sampling frequency so that is good news.

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