$computerSystemRef = $wsmanConnectionObject.NewReference("SELECT * FROM CIM_ComputerSystem WHERE Name='ManagedSystem'")
$computerSystemPackageRef = $wsmanConnectionObject.NewReference("CIM_ComputerSystemPackage")
$computerSystemPackageRef.AddSelector("Dependent", $computerSystemRef)
$computerSystemPackageInstance = $computerSystemPackageRef.Get()
$platformGUID = $computerSystemPackageInstance.GetProperty("PlatformGUID")