[PRTG] Get Last SelfTest from APC UPS

param(
    [string]$targethost,
    [int]$port = 161,
    [string]$version = "2c",
    [string]$community = "public",
    [string]$oid = "1.3.6.1.4.1.318.1.1.1.7.2.4.0",
    [string]$dateformat = "MM/dd/yyyy"
)

$pinfo = New-Object System.Diagnostics.ProcessStartInfo
$pinfo.FileName = "C:\Program Files (X86)\PRTG Network Monitor\Custom Sensors\EXE\snmpget.exe"
$pinfo.RedirectStandardError = $true
$pinfo.RedirectStandardOutput = $true
$pinfo.UseShellExecute = $false
$pinfo.CreateNoWindow = $true
$pinfo.Arguments = @("-q","-r:$targethost","-p:$port","-v:$version","-c:$community","-o:$oid")
$p = New-Object System.Diagnostics.Process
$p.StartInfo = $pinfo
$p.Start() | Out-Null

$stdout = $p.StandardOutput.ReadToEnd()
$stderr = $p.StandardError.ReadToEnd()
$p.WaitForExit()

function Convert-DateString ([String]$Date, [String[]]$Format)
{
   $result = New-Object DateTime

   $convertible = [DateTime]::TryParseExact(
      $Date,
      $Format,
      [System.Globalization.CultureInfo]::InvariantCulture,
      [System.Globalization.DateTimeStyles]::None,
      [ref]$result)

   if ($convertible) { $result }
}
$Now = (Get-Date)
$LastSelfTest = (Convert-DateString -Date $stdout.TrimStart().TrimEnd() -Format $dateformat)
$Difference  = $Now - $LastSelfTest;

Write-Host ([string]::Format("{0}:Last self test was {0} days ago",$Difference.Days));