$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
}
$prev = $null
for ($k = 1; $k -le 10; $k++) {
    $nc  = ReadSym 'GVL_Sync.nCycles' ([uint64])
    $bs  = ReadSym 'GVL_Sync.bSync' ([bool])
    $nrs = ReadSym 'GVL_Sync.nReturnedSeq' ([uint64])
    $nm  = ReadSym 'GVL_Sync.nMismatch' ([int])
    $lag = [int64]$nc - [int64]$nrs
    $delta = if ($null -ne $prev) { $nm - $prev } else { 0 }
    $prev = $nm
    Write-Host ("{0,2}  nCycles={1,-8} lag={2,4}  bSync={3}  nMismatch={4}  delta={5}" -f $k, $nc, $lag, $bs, $nm, $delta)
    if ($k -lt 10) { Start-Sleep -Seconds 60 }
}
$c.Dispose()