Modbus TCP Client
The modbus-tcp-client adapter is a network-transport port — it has no
serial device. Instead it connects out over the network to one or more
upstream Modbus/TCP servers, polls a configured list of points, and
republishes the results to MQTT, REST, and webhooks.
Use it to bring a Modbus/TCP device (a PLC, an energy meter, a VFD with an Ethernet card) into the same MQTT/webhook fabric as your serial buses — and to run a useful OmniBus instance on a plain VM with no USB hardware at all.
Configuration
- Upstream server(s) — host/IP and TCP port (Modbus/TCP default is 502).
- Point list — the registers/coils to poll, their unit id, function code, address, and quantity, plus a poll interval.
Outputs
| Output | Behavior |
|---|---|
| TCP | Not the primary path (this adapter is itself a TCP client). |
| MQTT | Publishes polled point values under the port prefix. |
| REST | Read/trigger actions. |
| Webhooks | Fan out polled values. |
See Modbus RTU for the shared request/response JSON shape, and Integrations → MQTT for topic conventions.