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Important topics that must be taken into account during the development
This documentation lists some important information what to think about when creating driver extensions
Because zenon drivers are system services, they are not indented to have a user interface at all.
If the driver extension returns true at Method SubscribeAsync zenon supposes that the communication is notification-based, that means the driver extension is able to call IValueCallack.SetValue(..) as needed. Otherwise, the communication is polling based, that means during execution of the ReadAll() method it is expected that IValueCallack.SetValue(..) gets called for new variable values or status changes.
The timestamp defined in IValueCallack.SetValue(..) represents the external timestamp (date and time the value is changed on the device). The internal timestamp (zenon received the value changed) is set internally.
Set CopaData.Drivers.Contracts.StatusBits.Spontaneous for new variable values, set CopaData.Drivers.Contracts.StatusBits.Invalid when circumstances lead to invalid values (e. g. connection loses)