param([int]$Samples = 20, [int]$IntervalMs = 500)
$ErrorActionPreference = 'Stop'
$adsDll = 'C:\Program Files (x86)\Beckhoff\TwinCAT\3.1\Components\Base\v170\TwinCAT.Ads.dll'
Add-Type -Path $adsDll
$c = New-Object TwinCAT.Ads.TcAdsClient
$c.Connect('169.254.176.217.1.1', 851)
function ReadSym($name, $type) {
    $h = $c.CreateVariableHandle($name)
    $v = $c.ReadAny($h, $type)
    $c.DeleteVariableHandle($h)
    return $v
}
$lags = New-Object System.Collections.Generic.List[int]
for ($k = 0; $k -lt $Samples; $k++) {
    $lag = ReadSym 'GVL_Sync.nMatchLag' ([int])
    $bs  = ReadSym 'GVL_Sync.bSync' ([bool])
    $lags.Add($lag)
    Write-Host ("{0}  lag={1,4} cyc  bSync={2}" -f (Get-Date -Format 'HH:mm:ss'), $lag, $bs)
    if ($k -lt $Samples - 1) { Start-Sleep -Milliseconds $IntervalMs }
}
$s = $lags | Sort-Object
Write-Host ("min={0} p50={1} max={2} mean={3:F2}" -f $s[0], $s[[int]($Samples/2)], $s[$Samples-1], (($lags | Measure-Object -Average).Average))
$c.Dispose()