Janitza UMG511
The Janitza UMG 511 is a three-phase power quality analyzer for industrial plants and commercial buildings, used for continuous electrical monitoring at the grid connection point or sub-distribution level. This Modbus RTU template reads per-phase voltage, current, active power, and reactive power across all three phases, plus total active power, total reactive power, grid frequency, and cumulative active consumption and production energy counters. With these registers in your ModbusCloud portal, you can track load balance, detect power quality deviations, and verify energy flows without additional software.
- Protocol
- Modbus RTU
- Connection
- RS485
- Registers
- 17, read only
- Brand
- Janitza
- Last updated
Registers (17)
17 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| voltage_l1 | V | Read | |||
| voltage_l2 | V | Read | |||
| voltage_l3 | V | Read | |||
| current_l1 | A | Read | |||
| current_l2 | A | Read | |||
| current_l3 | A | Read | |||
| active_power_l1 | W | Read | |||
| active_power_l2 | W | Read | |||
| active_power_l3 | W | Read | |||
| reactive_power_l1 | W | Read | |||
| reactive_power_l2 | W | Read | |||
| reactive_power_l3 | W | Read | |||
| active_power | W | Read | |||
| reactive_power | var | Read | |||
| frequency | Hz | Read | |||
| active_consumption_energy | Wh | Read | |||
| active_production_energy | Wh | Read |
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Use cases
- Monitor per-phase voltage on L1, L2, and L3 to detect supply imbalances before equipment is damaged.
- Track cumulative active consumption and production energy to generate tenant or cost-center sub-metering reports.
- Alert on total reactive power deviations to identify capacitor bank failures or lagging load conditions.
- Compare per-phase active power readings to verify even load distribution across the three phases.
- Record grid frequency over time to flag periods of off-nominal frequency that could affect sensitive machinery.
Installation
Enable Modbus RTU on the UMG 511 by navigating to the Communication menu on the device, then set a unique device address and matching baud rate for your bus.
Wire the RS485 bus to the UMG 511's 9-pin DSUB socket using a twisted, shielded cable; if the UMG 511 is the last device on the bus, switch the built-in termination resistor to ON.
In the ModbusCloud portal, add a new ModbusCloud Gateway, import the Janitza UMG511 template, and assign the Modbus unit ID you configured on the device.
Spot-check the connection by reading the frequency register (address 3995) in the portal's live register view and confirming it shows a value near 50 Hz.
Things to watch for
All register values read as zero or NaN. What is wrong?
The UMG 511 encodes all measured values as 32-bit IEEE 754 floats spanning two consecutive 16-bit registers in big-endian word order (high word first). If your gateway or parser is set to little-endian or swapped word order, every float will decode incorrectly. Verify the word order setting in the ModbusCloud Gateway configuration matches big-endian.
The gateway connects but no data appears after importing the template.
Confirm the Modbus unit ID in the portal matches exactly what is configured on the UMG 511's Communication menu. Also verify the baud rate, parity, and stop-bit settings are identical on both ends. A mismatch in any of these parameters will cause the device to ignore all requests silently.
RS485 communication is unreliable and timeouts occur frequently.
Check that termination resistors are enabled at both physical ends of the RS485 bus. The UMG 511 has a built-in termination switch on its DSUB socket; switch it to ON if the device is at the end of the line. Use a twisted, shielded cable and connect the cable shield at one end only to avoid ground loops.
Energy counter values seem frozen even though power readings are changing.
The active consumption (address 19068) and active production (address 19076) counters are stored as float32 and accumulate over time. At high energy totals the floating-point resolution decreases, which can make small increments invisible. This is normal behavior. Check that the UMG 511 has not had its energy counters manually reset via the device menu or via a factory reset.
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