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+--- Thread: KNX Topology (KNX IP or MQTT) (/showthread.php?tid=3501)
KNX Topology (KNX IP or MQTT) - jmir - 04.08.2021
We’re on a project where we have several KNX TP Lines (one for each building floor) and a Backbone TP Line (this must be maintained because there are some devices on it) (structure like attached file).
On each KNX Line there are several TP devices and a Logic Machine (used for visualization and to read some modbus RS485 sensors and meters).
Each floor can be rented by a different customer and the base floor is where the central Logic Machine is placed (inside KNX Line 1).
Each customer only needs to have access to his visualization and the central Logic Machine needs to have access (for example via frames) to all the floors and receive some data from meters (mapped to each Logic Machine from modbus RS485), Dali device errors, ....
If all Logic Machines are on the same Ethernet Network and we have KNX IP features enabled, we’ll have telegram repetitions between KNX Lines and IP, isn’t it?
At the same time we need to use Logic Machines (at least one of them) to program KNX devices if needed.
One option we’ve been testing is keeping KNX IP features enabled and using filter tables on Logic Machines block all traffic from TP to IP and from IP to TP (DST group policy = Accept selected group addresses and leaving Group address list blank). It seems that doing this we don’t have repetitions between TP and IP lines.
Then, to send values from modbus meters to the central Logic Machine, we’ve been thinking on two options:
1 – Use a specific group address range and let them pass trough Logic Machine filter (only over IP because TP couples will not have them on their filter tables)
2 – Enable MQTT broker on the central Logic Machine and post data from other Logic Machines mapping this to virtual group addresses on the central one.
Which would be the best configuration option? Our aim is to reduce to the maximum KNX traffic over backbone TP line (which can’t be over IP because there are several TP devices connected to it)
RE: KNX Topology (KNX IP or MQTT) - Daniel - 04.08.2021
This is unusual topology. In this case I would do it via Modbus (slave script on slave LM and profile on central) or MQTT use what is easier for you.
RE: KNX Topology (KNX IP or MQTT) - jmir - 10.08.2021
(04.08.2021, 07:56)Daniel. Wrote: This is unusual topology. In this case I would do it via Modbus (slave script on slave LM and profile on central) or MQTT use what is easier for you.
Ok. Thanks for your answer!