$port = New-Object System.IO.Ports.SerialPort COM10,600,None,8,one

try {
    $port.Open()

    [byte[]]$request = 0x57,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x1F,0x20

    $port.Write($request, 0, $request.Length)

    $response = New-Object System.Collections.Generic.List[byte]

    $timeout = [DateTime]::UtcNow.AddSeconds(2)

    while ([DateTime]::UtcNow -lt $timeout) {

        while ($port.BytesToRead -gt 0) {
            $buffer = New-Object byte[] $port.BytesToRead
            $count = $port.Read($buffer, 0, $buffer.Length)

            for ($i = 0; $i -lt $count; $i++) {
                $response.Add($buffer[$i])
            }
        }

        # Auf das Startbyte 57 synchronisieren.
        $start = $response.IndexOf([byte]0x57)

        if ($start -ge 0 -and ($response.Count - $start) -ge 12) {
            $response = [System.Collections.Generic.List[byte]](
                $response.GetRange($start, 12)
            )
            break
        }

        Start-Sleep -Milliseconds 20
    }

    if ($response.Count -eq 12) {
        $actual = ($response |
            ForEach-Object { "{0:X2}" -f $_ }) -join " "

        $expected = "57 07 01 06 00 01 03 06 02 00 01 20"

        Write-Host "Bytes empfangen: $($response.Count)"
        Write-Host "Antwort: $actual"

        if ($actual -eq $expected) {
            Write-Host "TEST ERFOLGREICH"
        }
        else {
            Write-Host "TEST FEHLGESCHLAGEN"
            Write-Host "Erwartet: $expected"
        }
    }
    else {
        Write-Host "Bytes empfangen: $($response.Count)"

        if ($response.Count -gt 0) {
            $actual = ($response |
                ForEach-Object { "{0:X2}" -f $_ }) -join " "
            Write-Host "Antwort: $actual"
        }
        else {
            Write-Host "Keine Antwort"
        }

        Write-Host "TEST FEHLGESCHLAGEN - keine vollstaendige Antwort gefunden"
    }
}
finally {
    if ($port.IsOpen) {
        $port.Close()
    }

    $port.Dispose()
    $port = $null

    [GC]::Collect()
    [GC]::WaitForPendingFinalizers()
}