All register reads return zero or an error. What is wrong?

Confirm the UMD96 has a fixed IP address and is reachable on port 502 from the ModbusCloud Gateway. By default the device uses DHCP, so the IP may have changed after a power cycle. Assign a static address in ENVIS or the device web interface and update the portal accordingly.

Voltage values look correct but power readings are all zero.

Check that current transformer inputs are wired and the CT ratio is correctly configured on the meter. The UMD96 calculates active and reactive power internally from voltage and current; if the current inputs are open or the CT ratio is set to zero, power registers will read zero even when voltage is present.

Phase power values seem swapped or sign is unexpected.

The UMD96 operates in six-quadrant mode, so active power per phase can be positive or negative depending on energy flow direction. Verify that voltage and current terminal wiring matches the phase sequence documented in the UMD96 installation manual, and that the CT polarity markings face the correct direction.

Register reads time out intermittently under high poll rates.

The UMD96 Modbus TCP server processes requests sequentially. Reduce your poll interval to no less than 500 ms between requests, or consolidate reads into fewer multi-register burst reads where addresses are contiguous. Grouping voltages (4352 to 4356), currents (4608 to 4612), and power values (4884 to 4908) into three separate reads reduces round-trips significantly.

Free Modbus template: PqPlus UMD96

The PqPlus UMD96 is a three-phase front panel energy meter designed for switchboard and distribution panel monitoring in commercial and industrial buildings. Using Modbus TCP, this template reads per-phase voltages on L1, L2, and L3, per-phase currents, total and per-phase active power, total reactive power, and grid frequency. Per-phase active and reactive power registers give the resolution needed to detect load imbalances across phases. Connecting the UMD96 to the ModbusCloud Gateway brings all fifteen measurement channels into a single cloud dashboard with historical trending and threshold alerts.

Name	Address	Function	Type	Unit	Access
frequency Grid frequency in hertz, typically 50 Hz in EU installations.	4100	FC03	float32	Hz	R
voltage_l1 Phase-to-neutral RMS voltage on phase L1.	4352	FC03	float32	V	R
voltage_l2 Phase-to-neutral RMS voltage on phase L2.	4354	FC03	float32	V	R
voltage_l3 Phase-to-neutral RMS voltage on phase L3.	4356	FC03	float32	V	R
current_l1 RMS current on phase L1 in amperes.	4608	FC03	float32	A	R
current_l2 RMS current on phase L2 in amperes.	4610	FC03	float32	A	R
current_l3 RMS current on phase L3 in amperes.	4612	FC03	float32	A	R
active_power Total three-phase active power in watts.	4884	FC03	float32	W	R
reactive_power Total three-phase reactive power in volt-amperes reactive.	4886	FC03	float32	var	R
active_power_l1 Active power on phase L1 in watts.	4896	FC03	float32	W	R
active_power_l2 Active power on phase L2 in watts.	4898	FC03	float32	W	R
active_power_l3 Active power on phase L3 in watts.	4900	FC03	float32	W	R
reactive_power_l1 Reactive power on phase L1 in volt-amperes reactive.	4904	FC03	float32	W	R
reactive_power_l2 Reactive power on phase L2 in volt-amperes reactive.	4906	FC03	float32	W	R
reactive_power_l3 Reactive power on phase L3 in volt-amperes reactive.	4908	FC03	float32	W	R