<#
    .SYNOPSIS
        Retrieve Last bootup information

    .DESCRIPTION
        This function will connect to remote computers to retrieve their last boot timestamp.

    .PARAMETER ComputerName
        Name of computer system to query

    .PARAMETER Credential
        Credential object to use when connecting to remote computers

    .EXAMPLE
        PS C:\> Get-PCUptime -ComputerName 'server1','server2'

        This example will connect to the two computers listed and retrieve their last boot time
        information using the security context of the user running the script

    .EXAMPLE
        PS C:\> $cred = Get-Credential
        Get-PCUptime -ComputerName 'server1','server2' -Credential $cred

        This example will connect to the two computers listed and retrieve their last boot time
        information using the security context of the credential created when calling Get-Credential

    .NOTES
        Additional information about the function.
#>
function Get-PCUptime
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string[]]$ComputerName,
        [ValidateNotNullOrEmpty()]
        [pscredential]$Credential
    )

    begin
    {
        #no prep work needed for this function
    }

    process
    {
        foreach ($name in $ComputerName)
        {

            # use splatting to add credential parameter if present when called
            $obj = New-Object psobject -Property @{
                ComputerName     = $name;
                LastBootUpTime   = $null;
                Uptime           = $null
            }

            try
            {
                #any exception in this block causes script to fall back to DCOM for connection to remote server
                $arguments = @{
                    ComputerName   = $name;
                    ErrorAction    = 'Stop'
                }

                if ($Credential)
                {
                    $arguments.Add('Credential', $Credential)
                }

                $session = New-CimSession @arguments
                $OS = Get-CimInstance -CimSession $session -ClassName Win32_OperatingSystem -ErrorAction Stop
            }

            catch
            {
                try
                {
                    $SessionOption = New-CimSessionOption -Protocol DCOM

                    $arguments = @{
                        ComputerName    = $name;
                        ErrorAction     = 'Stop';
                        SessionOption   = $SessionOption
                    }

                    if ($Credential) { $arguments.Add('Credential', $Credential) }

                    $session = New-CimSession @arguments
                    $OS = Get-CimInstance -CimSession $session -ClassName Win32_OperatingSystem -ErrorAction Stop
                }

                catch
                {
                    'Connection to server {0} failed' -f $name | Write-Error
                }
            }

            try
            {

                $LastBootTime = $OS | Select-Object -ExpandProperty LastBootUpTime

                $obj.LastBootUpTime = $LastBootTime

                $obj.Uptime = New-TimeSpan -Start $LastBootTime -End (get-date)
                $obj

            }

            catch
            {
                'Unable to retrieve last boot time on server {0}' -f $name | Write-Error
                $obj
            }
        }
    }

    end
    {
        # no cleanup code needed in this function
    }
}

if (!$cred) { $cred = Get-Credential}
Get-PCUptime -ComputerName 'miw059wt-cmtest','miw070wt-cmtest' -Credential $cred