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Problem with serial ports over bluetooth RRS feed

  • Question

  • All,

    I am trying to communicate with commercial survey instruentation via bluetooth.  I have two models of the device(an ES 105 and a GM 105).

    My application is a VB desktop WPF application.
    Windows version is 10

    The application I am using works fine with both devices using a wired serial connection(I can use either wired or bluetooth).

    One of the devices works just fine with bluetooth(the GS 105).

    The other device(the GM 105) works the first time I connect to it until I close the port(either explicitly or just by closing the application without having performing the close).

    After that point, all attempts to open the serial port result in this error 'The network location cannot be reached. For information about network troubleshooting, see Windows Help.'.

    At this point, the only thing I can do to make it work is to unpair the device and pair it again.  This eventually works, but not reliably.

    My observations on the problem:
    1) closing and opening the application makes no difference
    2) power cycling the device makes no difference
    3) rebooting the windows machine makes no difference
    4) updating the drivers in question makes no difference
    5) trying an external bluetooth dongle makes no difference
    6) I have written a completely independent and separate application in C++ to attempt the same thing and the behavior is exactly the same.
    7) the problem happens whether any data is written to the port or not
    8) deleting and explicitly adding the outgoing serial port(we use the OG port) makes no difference.
    9) while it serves no functionality, I can open and close the incoming port with no issues

    more information:

    You can monitor the device in bluetooth settings(Show Bluetooth Devices).  This page will list the devices and their status(Paired or Connected).

    If I monitor the device from start to finish, here is what I see(note that I do not send any data for this test):
    1) pair with the device
    2) the device is shown as 'Paired'
    3) I open the serial port
    4) I get a good status indicating that the port was opened
    5) the device status changes to 'Connected'
    6) I close the serial port
    7) the device status changes to 'Paired'
    8) I open the serial port again
    9) the device status changes to 'Connected' and then after a short period changes to 'Paired'
    10) I get the error message that the port could not be opened

    I can then repeat items 8, 9, and 10

    So successive attempts to open the port appear to actually connect to the device breifly and then it fails and I get the error that indicates the port was not opened.

    It seems that closing that port corrupts the virtual connection in some persistent fashion(but only for one of the devices)

    Does anyone have any thoughts as to how I might proceed to resolve this? I am considering opening a ticket with the device manufacturer, but I suspect they will be inclined to say(rightfully so) that is a windows problem.

    Thanks much



    • Edited by TPG713 Friday, August 24, 2018 7:39 PM
    Friday, August 24, 2018 3:43 PM

All replies

  • Sounds like an issue with the device or compatibility.  What version of Bluetooth does the device use?  What version is the PC using?

    Have you verified the behavior on a different PC?

    If the Bluetooth versions are the same and the behavior persists on another system then you most likely do have a problem with the device and need to contact the manufacturer for support.

    Whether it is a device or connectivity issue, it doesn't sound like it is a VB Language issue so we may not be able to assist much more than these general suggestions.


    Reed Kimble - "When you do things right, people won't be sure you've done anything at all"

    Saturday, August 25, 2018 2:43 PM
    Moderator