Called if you have subscribed to continuous updates from the control thread, or if there is
data returned from the TRealtime counterpart.
This is guaranteed to be invoked before Dispose if there's any data that's been sent
from Pipe.SendData and suitable flags have been set in
ProcessorInstance.CreationParameters.controlUpdateSetting.
Additional resources: ControlContext.Manual.Update, ControlContext.ProcessorUpdateSetting