Public/Get-Uptime.ps1

function global:Get-Uptime
{
    <#
        .EXTERNALHELP HelperFunctions.psm1-Help.xml
    #>


    [CmdletBinding()]
    [OutputType([pscustomobject])]
    Param
    (
        [Parameter(Mandatory = $false)]
        [string]$ComputerName,
        [Parameter(Mandatory = $false)]
        [System.Management.Automation.PsCredential]$Credential
    )

    Begin
    {
        #Enable TLS 1.2
        [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

        [String]$dtmFormatString = "yyyy-MM-dd HH:mm:ss"
        $ns = 'root\CIMv2'
    }
    Process
    {
        $params = @{
            NameSpace    = $ns
            ErrorAction  = 'Continue'
        }

        If (($PSBoundParameters.ContainsKey('ComputerName') -eq $true) -and ($null -ne $PSBoundParameters['ComputerName']))
        {
            $params.Add('ComputerName', $ComputerName)
        }
        Else
        {
            $ComputerName = [System.Net.Dns]::GetHostByName("LocalHost").HostName
        }

        If (($PSBoundParameters.ContainsKey('Credential') -eq $true) -and ($null -ne $PSBoundParameters['Credential']))
        {
            $params.Add('Credential', $Credential)
        }

        Try
        {
            $objOS = Get-CimInstance -ClassName Win32_OperatingSystem @params

            If ($null -ne $objOS)
            {
                $uptimeTimespan = New-TimeSpan -Start $objOS.LastBootUpTime.ToUniversalTime() -End $objOS.LocalDateTime.ToUniversalTime()
                $uptime = New-Object System.TimeSpan($uptimeTimespan.Days, $uptimeTimespan.Hours, $uptimeTimespan.Minutes, $uptimeTimespan.Seconds)
                $lastBootupTime = $objOS.LastBootUpTime.ToString($dtmFormatString)
                $lastBootupTimeUTC = $objOS.LastBootUpTime.ToUniversalTime().ToString($dtmFormatString)
            }
        }
        Catch
        {
            $objOS = Get-WmiObject -Class Win32_OperatingSystem @params
            If ($null -ne $objOS)
            {
                $uptimeTimespan = New-TimeSpan -Start ($objOS.ConvertToDateTime($objOS.LastBootUpTime)).ToUniversalTime() -End ($objOS.ConvertToDateTime($objOS.LocalDateTime)).ToUniversalTime()
                $uptime = New-Object System.TimeSpan($uptimeTimespan.Days, $uptimeTimespan.Hours, $uptimeTimespan.Minutes, $uptimeTimespan.Seconds)
                $lastBootupTime = ($objOS.ConvertToDateTime($objOS.LastBootUpTime)).ToString($dtmFormatString)
                $lastBootupTimeUTC = (($objOS.ConvertToDateTime($objOS.LastBootUpTime)).ToUniversalTime()).ToString($dtmFormatString)
            }
        }
    }
    End
    {
        Return [PSCustomObject]@{
            Computer            = $ComputerName
            Uptime           = $uptime
            LastBootTimeUTC   = $lastBootupTimeUTC
            LastBootTimeLocal = $lastBootupTime
        }
    }
} #End function Get-Uptime