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Thread: Micro-Can or HEX-USB+CAN for Mk7 GTI

  1. #1
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    Question Micro-Can or HEX-USB+CAN for Mk7 GTI

    I drive a Mk7 GTI (2015) am trying to decide on which Ross-Tech cable to buy, the Micro-CAN or the HEX-USB+CAN. I have read the Ros-Tech website and have done searches to help clarify what the differences are and cannot seem to find much specifics.

    As I understand it the HEX-USB+CAN can be used on older models and the newer Audis. I have read that it may have a faster sample rate by using the "Turbo" mode in the software. I have read on forums that there are other limitations of the Micro-CAN, but no one has said specifically what they are.

    My questions are:

    1. Is the sample rate for logging better when using the HEX-USB+CAN, or does that only concern older vehicles?
    2. What other limitations does the Micro-CAN have if any?

  2. #2
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    Sample rate difference is well under 10% between the two devices. When the HEX can activate the Turbo mode of the controller, then the HEX is much faster. In the manual for VCDS and on this particular page, we state the following concerning sample rates:

    Sample Rate: Some ECUs may not be willing to produce more than about 3.5 samples per second when running a single group, even with the most aggressive protocol-timing settings. Other ECUs may be much faster. Except on the slowest most ancient PCs, this is a limitation inherent in the firmware in the ECU, not a limitation in the VCDS software or the PC. Naturally, if two groups are being displayed simultaneously, the sample rate drops about half what it was running a single group, and 3 groups simultaneously runs at around 1/3. Sample Rate will vary from controller to controller.

    Some controllers (particularly AG4 transmissions and Digifant-III ECU's) use a "hybrid" data-type that requires reading a long header when changing group numbers. Viewing multiple groups still works with these data types, but the sample rate becomes extremely slow. If you see "Reading Header" all the time under the Sample Rate display, you'll know you've got one of these.

    In Engine controllers using KWP-2000 or CAN, there is a [Turbo] button in Measuring Blocks screen. Pressing this button can significantly speed up sampling, for example over 30 samples per second when logging a single group in our Touareg. Once you have pressed [Turbo] you will remain in this High-Speed mode until you exit the Measuring Blocks screen. Some combinations of ECUs and PCs may not play well with this function so if you get undesirable results like a dropped session or bogus data, you should exit out of the controller and get back into Measuring Blocks but without clicking on [Turbo]. This function is only available when using a HEX Interface.
    So, if you plan to do a lot of engine performance monitoring, the HEX-USB+CAN should be your choice.

    Other than the limitations of vehicle models supported, there are no other "limitations" of the MicroCAN.
    Last edited by Bruce; 08-04-2015 at 06:55 AM. Reason: added the link to the manual - "this particular page"

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  4. #3
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    Thanks Bruce! I'll be buying the HEX-USB+CAN so I'm not limited on sample rate.

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    Quote Originally Posted by Bruce View Post
    Sample rate difference is well under 10% between the two devices. When the HEX can activate the Turbo mode of the controller, then the HEX is much faster. In the manual for VCDS and on this particular page, we state the following concerning sample rates:



    So, if you plan to do a lot of engine performance monitoring, the HEX-USB+CAN should be your choice.

    Other than the limitations of vehicle models supported, there are no other "limitations" of the MicroCAN.
    Bruce: Hi
    A question without notice - please (to quote a vernacular from our Parliamentary process which we thieved from our UK founders): For those cases where the car's equipment does allow
    Turbo mode, has Ross Tech published any material regarding the PC/Laptop limitations for Turbo mode?
    Thanks in advance
    Don
    VW Golf MkVII (MY13) - A3 8V hatch (MY17)

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    Benevolent Dictator Uwe's Avatar
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    Anything resembling a modern PC should not be a limiting factor.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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