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Modbus with VOOL: chargers, the LMC and Home Assistant

Modbus TCP is supported on VOOL chargers and the LMC. How it is enabled, where the register map is, and what to check when a local integration stops working.

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Written by Juhan Harm

Yes — Modbus is supported. VOOL chargers expose a Modbus TCP/UDP interface, and the LMC exposes Modbus as well. This is the supported route for local integrations such as Home Assistant.

Enabling Modbus on a charger

The interface is disabled by default. It is enabled with the charger parameter 522 — Enable Modbus TCP/UDP interface. Once enabled, the interface listens on port 502 (TCP and UDP); the parameter number 522 is not the port. Modbus runs on the same single interface (Ethernet or Wi-Fi) as the charger's other traffic — a hybrid setup with Modbus on one and OCPP on the other is not supported.

If you cannot find or change this setting yourself, VOOL support can enable Modbus remotely for a given serial number, usually within a working day.

Enabling Modbus on the LMC

On the LMC, Modbus is enabled from the LMC's own interface: installer mode → OCPP settings → enable Modbus. Support can also enable it remotely on request.

Register map

The charger's Modbus registers — live state, currents, voltages, power, energy, plus writable registers for start/stop, an external current limit and allowed phases — are documented in full in the Charger Modbus manual in this help centre.

If a working integration stops responding

  • Check the device's current IP address first. After a firmware update or a router change the charger's LAN IP can change, and the integration then polls an address that no longer exists. The charger's current IP is visible in the web portal — compare it with the address configured in your integration before assuming the interface is off.

  • Set a static IP (or a DHCP reservation) for chargers and the LMC in your router. Router-assigned address changes have also broken load-management communication at multi-charger sites.

  • Check the device is on the same subnet as the machine polling it, and remember the interface allows at most 3 simultaneous connections.

Security note

The Modbus interface has no authentication. Use it only in local, secure networks.

Community integrations and partner APIs

There are third-party Home Assistant integrations for VOOL hardware. They are not built or maintained by VOOL, and some do not work with the LMC without adjustment. For questions about a community integration, please contact its author.

Modbus and OCPP are the documented integration paths. For partner or developer API questions, email [email protected] with your questions numbered and we will route them internally.

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