This node is used to bridge multiple KNX Ultimate gateways (multiple knxUltimate-config) using Node-RED wires.

It outputs RAW telegram information (APDU + cEMI hex + addresses) for every telegram received from the KNX bus of the selected gateway. It can also accept those RAW telegram objects on its input and forward them to the selected gateway.

Server KNX/IP mode

Set Mode to Server KNX/IP to start an embedded KNXnet/IP tunneling server (UDP). Incoming client telegrams are emitted as the same RAW format used by MultiRouting. The node also accepts RAW telegram objects on its input and injects them to the connected tunneling client(s).

Important (Advertise host): KNXnet/IP clients will send data to the IP advertised by the server in the CONNECT_RESPONSE. If the client shows connected but the server receives no telegrams, set Advertise host to the server LAN IP reachable by the client (especially when running Node-RED in Docker/VM or on a multi-homed host).

Output message format

msg.payload contains:

  • knx.event: GroupValue_Write / GroupValue_Response / GroupValue_Read
  • knx.source: physical address (e.g. 1.1.10)
  • knx.destination: group address (e.g. 0/0/1)
  • knx.apdu.data: raw APDU payload as Buffer (only for Write/Response)
  • knx.apdu.bitlength: payload bit length (<=6 means encoded in APCI low bits)
  • knx.cemi.hex: full cEMI hex (ETS-like)
  • knx.echoed: true if echoed by the gateway
  • knxMultiRouting.gateway: gateway meta (id, name, physAddr)

Routing counter (hop count)

MultiRouting can use the KNX routing counter (hop count) found in knx.cemi.hex to prevent telegram loops.

  • Respect routing counter (drop if 0): telegrams with routing counter 0 are not forwarded.
  • Decrement routing counter when routing: the node decrements the routing counter while forwarding. If it reaches 0, the telegram is dropped.

The current value is exposed as knx.routingCounter (and as knx.cemi.hopCount when knx.cemi is an object).

Rewriting telegrams

If you rewrite knx.source / knx.destination in your flow, you must also keep knx.cemi.hex coherent. Recommended: place KNX Router Filter between MultiRouting nodes: it will keep knx.cemi.hex in sync when rewriting.

Notes

  • When forwarded to another gateway, the source physical address will change (it becomes the sender gateway address). Use knx.source and/or knxMultiRouting.gateway to filter loops.
  • The option Drop messages already tagged for this gateway helps prevent simple loops when you connect multiple routers together.