Send-MqttOnPowerStateChange Powershell Script

About

On Windows, this script can be called from a Task Scheduler job to send a message to MQTT. I use this to communicate with Home Assistant that my PC has woken up.

Prerequisites

M2Mqtt Nuget Library

Thanks to Alexander Gruber at https://jackgruber.github.io/2019-06-05-ps-mqtt/ for his sharing how to use the M2Mqtt nuget library.

Download the M2Mqtt library manually, or by nuget.exe. The nuget.exe can be downlaoded here.

nuget.exe install M2Mqtt -o c:\lib

In Powershell, the DLL can then be included via Add-Type -Path "C:\lib\M2Mqtt.4.3.0.0\lib\net45\M2Mqtt.Net.dll" so that the contained classes can be used.

Set Environment Variables

Set up the following environment variables with the appropriate values:

• MQTT_HOST
• MQTT_PORT
• MQTT_USERNAME
• MQTT_PWD

Wake Up - Create Task Scheduler Job

Create a Windows Task Scheduler job with the following properties:

General

Run whether user is logged on or not.

Running as SYSTEM or running with elevated privileges is not necessary.

Triggers for Wake

Create a trigger to begin the task "On an event"

Log: System

Source: Power-Troubleshooter (be careful, there may be 2 of these in the list. If one doesn't work, try the other.)

Event ID: 1

Actions for Wake

Action: Start a program

Program/script: powershell.exe

Arguments: -ExecutionPolicy Bypass –NoProfile –Command "& {C:\Code\NotifyOnWake\Send-MqttOnPowerStateChange.ps1 -State wake; exit $LastExitCode}" >> %USERPROFILE%\wake.log

This structure for running scheduled tasks is what I've found works well to get the scripts last exit code reported back to Task Scheduler. Using powershell.exe's -File argument results in powershell.exe's exit code to be reported, not the script.

Settings

Check: Stop the task if it runs longer than 1 hour.

Shouldn't be necessary since the script has a number of retries embedded, but just in case...

Sleep - Create Scheduled Task

Only the following are different from the first task.

Triggers for Sleep

Create a trigger to begin the task "On an event"

Log: System

Source: Kernel-Power

Event ID: 187

Actions for Sleep

Action: Start a program

Program/script: powershell.exe

Arguments: -ExecutionPolicy Bypass –NoProfile –Command "& {C:\Code\NotifyOnWake\Send-MqttOnPowerStateChange.ps1 -State sleep; exit $LastExitCode}" >> %USERPROFILE%\sleep.log