Note that if the data is distributed through a triggered FanOut (i.e. variables from device is connected to other variables through a trigger, the usual way for poll-type variables) the data read from the receiving end of the variable cannot be considered valid if the DataValidity is faulty.
Additionaly, a change of to a faulty validity state will signal the availability of new data on those variables, which is to be considered invalid.
Bahnhof.Variables which are Constants or outputs of the ConfigReader and are connected to a DeviceModule should be written in an initialisation handler. Currently they are written in ConfigReader::pepare() etc., which might block the application initialisation if an exception occurs in the process of writing these variables.
