1. Automatic creation
Upon project creation ETS automatically sets the filter tables of all involved Couplers per Group Address.
If Group Address 'A' is the link between a Group Object of a device in line 1.1 and a Group Object of a device in line 15.15 then the Line Coupler 1.1.0, Backbone Coupler 1.0.0, Backbone Coupler 15.0.0 and Line Coupler 15.15.0 are the involved Coupler. ETS will automatically set (not download!) the Filter Tables of these four Couplers. If later on also a Group Object of a device line 1.2 will be added to the Group Address 'A' then ETS will update the filter table of the line coupler 1.2.0 too.
When downloading a coupler, ETS calculates the Group Address filter table based on the current usage of Group Addresses in the project. Whenever this usage changes (new Group Address links are being created or existing ones being removed), ETS calculated the possible impacts on the couplers of the project and resets the GRP programming flag on those couplers which need an update of their filter table. This informs the user about the need to re-download these couplers in order to enable his latest changes to work correctly.
In some cases, not all communication devices in the KNX installation are modeled as devices in the ETS project and therefore ETS is not able to take these devices and their Group Address links into account when calculating the filter table for the couplers. In these scenarios the installer must manually ensure that the required Group Addresses are forwarded into the network segment where this communication partner is located (e.g. a visualization tool). This was common practice at times, where bus interfaces were not modeled in ETS and the installer did not want to use so-called dummy devices because of their many drawbacks. To manually control the filter table, 3 tools are available:
- Setting the Group Address to "Pass through Line Coupler". This will punch a hole into all the filter tables of all the couplers in the entire project (resulting in the Group Address to appear "everywhere"). This setting is also available on group range level and automatically enables this setting on every Group Address with this group range.
- In the Topology view select the Line where the visualization system is connected to
- Click the 'Information' tab in the sidebar under 'Properties'
- Add the required Group Addresses manually
- Adding single Group Addresses and blocks of Group Addresses to a subnetwork segment. This will act independent of the "Pass through Line Coupler" flag on Group Address level and only affects the filter table of the one coupler responsible for connecting this subnetwork segment.
- Use of a dummy device
- Add one or more dummy devices to the line where the visualization system is connected to
- via the device parameters add the required Group Objects
- assign the required Group Addresses
Unfortunately, manually intervening the calculation of the filter table based on the project's Group Address links influences the capability of ETS to correctly detect the impact that changes of the Group Address configuration of the project might have on the filter tables of the project's couplers and the GRP programming flag might not be correctly reset.
3. How shall this be done nowadays
The bus interfaces are modeled in ETS, therefore one can drag'n'drop the required group addresses to the respective tunneling interfaces, an example of which is illustrated below, after which the group addresses are added to the Filter table of the respective couplers.
4. Filter table preview
Before the actual download it is possible to check the virtual filter tables, this can be done via the Coupler context menu.
5. Device info
Reads out the latest downloaded Filter Table from the Coupler's memory: this can be done via the Coupler context menu.