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WinBioEnumBiometricUnits can't find any WBF device which is emulated RRS feed

  • Question

  • I have install a WBF device and it' emulated in device manager.

    It's strange that WinBioEnumBiometricUnits can't find any WBF device

    the return parameter "unitCount" is aways zero

    It only happened in some platform.

    Does anyone see this issue/

    thanks 

    Thursday, May 23, 2019 9:39 AM

Answers

  • The source code almostly follow the sample code.

    KT

    Hello,

    I think your "WBF" device is a "WinBioFingerprint" device, and if you read the documentation, only this device is supported in the function. So I think, you pass the factor WINBIO_TYPE_FINGERPRINT already to the function.

    Regarding the code: What do you mean, your "source code almostly follow the sample code"? As long as we don't see how you call the function and how you defined the variables that you pass in the function, everything is speculation, as Suarez Zhou already said.

    Regarding the OS: It could be a problem in the old Windows 10 machine. You say the problem does not occur on many other Windows 10 machines which are more up to date. So why don't you just update the old Windows 10 machine? Maybe this can solve your problem already.

    Regards, Guido

    • Marked as answer by KT Liao Thursday, May 30, 2019 5:31 AM
    Friday, May 24, 2019 8:20 AM

All replies

  • Hello,

    please provide more information about how you try to open the device and call the function (source code).

    Here is an example: https://docs.microsoft.com/en-us/windows/desktop/api/winbio/nf-winbio-winbioenumbiometricunits

    Regards, Guido


    Edit: What is the return value of WinBioEnum..?
    Thursday, May 23, 2019 9:59 AM
  • Hi Guido,

    thanks.

    It's strange that APP has worked perfectly with many Win10 but meet issue in China's test machines

    From our FAE's debug log, the return of the function is OK but  unitCount is always zero.

    I just install a Win10 which is simple chinese version. it works fine.

    The source code almostly follow the sample code.

    Basicly I think the application should be ok(pass for 6~7 platform)

    but don't undserstand what happen in our customer side.

    Currently we know the OS version is 10.0.16299.15 (old Win 10)

    Please let me know if you have any advice.

    thanks

    KT

    Thursday, May 23, 2019 12:50 PM
  • Hello,

    Thank you for posting here.

    >>From our FAE's debug log, the return of the function is OK but  unitCount is always zero.

    After viewing Microsoft technology documents, I found a remark similar to your description of the problem. Here are the remark and link for your reference.

    If all of the factor bits in the Factor bitmask refer to unsupported biometric types, the function returns S_OK but the value pointed to by the UnitSchemaArray parameter will be NULL and the UnitCount parameter will contain zero. Although it is not an error to inquire about unsupported biometric factors, the result of the query will be an empty set.

    https://docs.microsoft.com/en-us/windows/desktop/api/winbio/nf-winbio-winbioenumbiometricunits

    As far as I'm concerned, you should pay attention to the acquisition of the parameter Factor. If the parameter factor acquisition fails, the return value of the function should be E_INVALIDARG. The type here may be not WINBIO_TYPE_FINGERPRINT, which leads to this error. Due to the lack of environment, we are sorry to be unable to speculate on the concrete reason.

    Best Regards,

    Suarez Zhou

    Friday, May 24, 2019 6:06 AM
  • The source code almostly follow the sample code.

    KT

    Hello,

    I think your "WBF" device is a "WinBioFingerprint" device, and if you read the documentation, only this device is supported in the function. So I think, you pass the factor WINBIO_TYPE_FINGERPRINT already to the function.

    Regarding the code: What do you mean, your "source code almostly follow the sample code"? As long as we don't see how you call the function and how you defined the variables that you pass in the function, everything is speculation, as Suarez Zhou already said.

    Regarding the OS: It could be a problem in the old Windows 10 machine. You say the problem does not occur on many other Windows 10 machines which are more up to date. So why don't you just update the old Windows 10 machine? Maybe this can solve your problem already.

    Regards, Guido

    • Marked as answer by KT Liao Thursday, May 30, 2019 5:31 AM
    Friday, May 24, 2019 8:20 AM
  • Thanks your comment,

    Yes, your proposal is right.

    We use Microsoft's WIn10 ISO and it worked perfectly.

    I think it's the problem of customer's ISO

    Tuesday, May 28, 2019 9:50 AM
  • Hi,

    Is your problem solved? If so, please mark the useful replies as answers.  

    Best Regards,

    Suarez Zhou


    • Edited by Suarez-Zhou Wednesday, May 29, 2019 3:20 AM
    Wednesday, May 29, 2019 1:15 AM