Janitza Modbus for Home Assistant

Custom Home Assistant integration for Janitza energy measurement devices over Modbus TCP.

The integration intentionally reads only the generic Janitza 19xxx holding register range so it can work across device families that expose the common measurement profile.

Features

• UI based setup through Home Assistant config entries
• Local polling over Home Assistant's shared Modbus TCP connection
• Batched reads of the 19xxx register block
• Auto-discovery of UMG 800 virtual meters and UMG 801 current module groups
• Energy dashboard friendly sensor metadata where applicable
• HACS compatible repository layout

Release 0.4.0

Migrates the integration to Home Assistant 2026.9's shared Modbus connection API. Home Assistant now owns connection setup, request serialization, reconnection, and shutdown while the Janitza-specific register maps, UMG 801 modules, UMG 800 modules, and virtual meters remain unchanged. This release requires Home Assistant 2026.9.0 or newer.

Release 0.3.0

Adds Modbus-only discovery for UMG 800 virtual meters while retaining the existing guarded UMG 801 module path. The UMG 800 is identified through its default Modbus device-name mapping before the integration reads the names and measurements of up to 32 virtual meters. Physical module metadata supplies fallback names when a meter has no configured name.

Release 0.2.2

Stability release for mixed Janitza device fleets. UMG 801 module discovery now runs only after the normal 19000 measurement block has been read, and module ranges are skipped unless UMG 801 slot metadata is present. This keeps UMG 96-PA and other common-profile devices on the original polling path.

Release 0.2.1

Small stability release. Non-finite Modbus float values such as nan and inf are now treated as unavailable sensor samples so Home Assistant does not reject numeric sensor state updates.

Release 0.2.0

This release adds UMG 801 current module support. The integration now probes the documented module measurement blocks from 19400 onward and creates module entities only for groups that answer over Modbus.

Installation with HACS

1. Add https://github.com/JanitzaElectronics/ha-janitza-modbus as a custom HACS integration repository.
2. Install Janitza Modbus.
3. Restart Home Assistant.
4. Add the integration from Settings > Devices & services.

Configuration

The setup flow asks for:

• Hostname or IP address
• TCP port, usually 502
• Modbus unit ID, often 2 for Janitza measurement registers
• Display name
• Poll interval in seconds

Supported registers

The initial register catalogue is deliberately small and uses only addresses in the generic 19xxx range. Register values are decoded as big-endian IEEE-754 32-bit floats from holding registers.

The current catalogue was checked against the Janitza UMG 96-PA and UMG 604-PRO Modbus address lists. It includes the commonly needed values from 19000 through 19120, including:

• Phase and line voltages
• Phase currents and vector current sum
• Per-phase and summed active, apparent, and reactive power
• Per-phase power factor
• Frequency
• Per-phase and total active, apparent, and reactive energy counters
• Voltage and current THD values

If a device exposes additional generic 19xxx values, add them in custom_components/janitza_modbus/registers.py.

The PDF lists summed active, apparent, and reactive power at 19026, 19034, and 19042. The adjacent addresses 19024, 19032, and 19040 are L3 phase values, not totals.

UMG 604-PRO also exposes additional values later in the 19xxx range, for example 19630+. Those are not enabled by default because the integration currently performs one contiguous read of the shared 19000 through 19120 block.

For UMG 801 devices, the integration probes the documented current module slot information area and then checks the corresponding module measurement blocks starting at 19400, 19500, 19600, and so on. For a UMG 800 using its default Modbus address list, the integration identifies the device at register 0 and independently discovers up to 32 named virtual meters. Their names are read at 1966, 2966, 3966, and so on; their four-channel measurements start at 1012, 2012, 3012, and so on. Physical module information from register 54 onward is used only as a fallback for unnamed meter groups. Only groups with readable finite measurements are added as entities. Digital-input and transfer modules do not create sensor entities.

The UMG 96-PA address list marks 19054 through 19058 and 19086 through 19090 as device-specific compared with other UMG-series devices. For that reason, the default catalogue uses the non-starred per-phase energy counters from 19062 onward.

Notes

Janitza devices and gateways may need Modbus TCP enabled in the device settings. Some installations also require firewall access to TCP port 502. If connection tests fail but Home Assistant's native Modbus integration works, double-check the Modbus unit ID. On some Janitza setups the generic 19xxx measurement registers are exposed on slave/unit 2 rather than 1.

The UMG 801 workbook in the repository documents a per-slot information area at 4178 + 80 * (slot - 1). In that block, +68 stores the slot state and +69 the module type. The integration uses that slot information to avoid probing UMG 801 module ranges on devices that do not expose UMG 801 module metadata.

UMG 800 module discovery requires the device's default Modbus address list. A customized active address list can relocate or remove the identity, slot, and measurement registers used for discovery.