How to programatically trigger "Modern" standby (desktop app)

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How to programatically trigger "Modern" standby (desktop app)

James Clark 6

Traditionally, desktop apps could use the SetSuspendState() API to suspend (S1-S3).

However, this no longer works on systems that support "modern" standby and fails with ERROR_NOT_SUPPORTED.

A workaround is to turn off the display. This triggers "modern" standby but cannot be (easily) done from a service application due to session 0 isolation.

What is the best way to trigger "modern" standby from a service?

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Answer 1

Jeanine Zhang-MSFT 11,356 Microsoft External Staff

Hi,

Welcome to Microsoft Q&A!

Modern Standby consists of multiple hardware and software power modes, all of which occur with the screen turned off.

I suggest you could try to use the SC_MONITORPOWER parameter for the WM_SYSCOMMAND message to turn off the monitor:

SendMessage(handle, WM_SYSCOMMAND, SC_MONITORPOWER, 2);

The argument 2 for the fourth parameter turns the monitor off.

You could refer to the Doc:
https://learn.microsoft.com/en-gb/windows/win32/menurc/wm-syscommand?redirectedfrom=MSDN

Best Regards,

Jeanine

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James Clark 6 Reputation points

2022-04-14T07:08:40.673+00:00

Thank you. I already tried this.

Unfortunately, the WM_SYSCOMMAND message approach cannot be used from a service due to session 0 isolation. I think this is because programs running in this session are isolated from the display.

Please, what is the best way to put such a system into the "modern" standby state? Previously, this was trivial using SetSuspendState()
Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2022-04-14T09:42:31.33+00:00

@James Clark

I suggest you could refer to the thread: https://stackoverflow.com/questions/71664584/windows-how-to-initiate-modern-standby-from-session-0

The Microsoft PwrTest tool achieves this by installing a virtual button driver and then pressing the virtual "power" button.
James Clark 6 Reputation points

2022-04-15T07:15:44.147+00:00

I wrote the Stackoverflow question!

Installing a fake keyboard driver to simulate a virtual sleep button is massive overkill. It was previously easy to get a PC to sleep. Is there really no better way on a "modern" PC?
Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2022-04-18T08:16:02.053+00:00

@James Clark

As far as I'm concerned, there is no suitable winapi to trigger "modern" standby from service.
If you want to suggest the feature, I suggest you could try to send the feedback to Microsoft with the Feedback Hub app.
James Clark 6 Reputation points

2022-04-21T16:08:12.477+00:00

That seems a pretty big break in backwards compatibility! On systems with "modern" standby, software can no longer programmatically suspend the PC yet can continue to hibernate and shutdown the system as before. That seems to be very inconsistent.

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How to programatically trigger "Modern" standby (desktop app)

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