Hi, Masahiro -
Although it appears to be possible to interface a Windows application via C/C++, it looks as though a direct implementation would require the use of callback functions, which PB does not support. There also appears to be a way to communicate with a Bluetooth device via Windows Sockets. I found the following URL that covers these topics:
https://learn.microsoft.com/en-us/windows/win32/bluetooth/about-bluetooth
It is possible for a PB application to utilize Windows Sockets. Roland Smith's TopWizProgramming website contains a free code sample that illustrates how a PB application can interface with Windows Sockets, but this example app does not specifically interface with Bluetooth (as far as I know):
https://www.topwizprogramming.com/freecode_winsock.html
There is additional Microsoft documentation regarding Bluetooth via Windows Sockets that can be accessed via the first URL listed above.
Depending on your C++ skills, it might be possible to create an interface between PB and Bluetooth using PBNI (PowerBuilder Native Interface). Theoretically, you could then use the C++ Bluetooth interface directly:
https://docs.appeon.com/pb2022r3/native_interface_programmers_guide_and_reference/index.html
Good luck and Best Regards, John