USB device and Windows shutdown

Question

Hello,

I am using a USB device that works like a USB keyboard connected to a USB port of PC or laptop. The USB device powered separately and the PC USB port is not providing the power to the USB device. .
I'd like to let the USB device know when Windows is shutting down on the PC or laptop.
Is there any messages, during Windows shut down, sent to the USB port that the USB device can be listening on?

Answer 1

Hello,
Welcome to Microsoft Q&A!

Windows shutdown will send WM_QUERYENDSESSION message to all programs, programs receive this message will automatically exit, your program if running will receive this message, as long as the program intercept the message and process.
So you can intercept to this message in the program and send Windows shutdown Message to your USB device via port.

https://learn.microsoft.com/en-us/windows/win32/shutdown/wm-queryendsession

About “How to distinguish shutdown between restart,” need access to system logs.
You can use ReadEventLog to read the System log when WM_QUERYENDSESSION, You can refer to this Querying for Event Information sample.

https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-readeventloga
https://learn.microsoft.com/en-us/windows/win32/eventlog/querying-for-event-source-messages

Thank you.

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