Stale points — KNX project

Why, when discovered points are added to the Database, some are {stale} and some are not?

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One of the many reasons why points can go to a {stale} state relates to the ETS project file.

When points are added to the Database from a ETS project file, their Subscription properties are automatically configured according to which Communications Flags are set in the ETS project, for the KNX Device's Group Objects which are associated with the point's Group Address.

If a Group Address has at least one KNX Device Group Object associated with it that has its Read Communication Flag property enabled then the Poll once on subscribed, Poll once on operational and Poll until answer after poll once properties are set to true. This will trigger an immediate poll of the Group Address (because this view is itself subscribed to the point).

If a Group Address has no associated KNX Device Group Objects that have their Read Communication Flag enabled then its Subscription properties will all be set to false by default. The value will however be updated (and become not {stale}) in the KNXnet/IP driver when any subsequent unsolicited messages regarding the Group Address are received from the KNX system.

Here are the Communications Flags settings for some of the points in the example shown above:

NOTE: The Control Output (Control value) object has its Transmit flag set. This will cause an unsolicited message transmission from the KNX device.

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