Is 19000 a one-based register number?

No. Janitza's address lists give the address that goes on the wire, so 19000 is sent as 4A 38. A tool that asks for one-based holding register numbers needs 19001, or 419001. If the first Float read returns a tiny or absurd value, the client is probably one register out.

Where are current inputs I5 to I8?

In measurement group 02. The list names its four currents I1 to I4 again, starting at 19200, and repeats the group 01 layout: total active power at 19214 and total active energy at 19244. Both groups share the voltages at 19000 to 19010.

How do I find the addresses for current measuring modules?

Each module measurement group has a 100-register block from 19400 upwards in the published list, but which blocks exist depends on the modules fitted. The device homepage shows the active Modbus address list and downloads it as a CSV file, including the module addresses. Switching to Virtual Meter mode generates a new list.

Can Edge read the RS-485 port when the UMG 801 is a Modbus gateway?

Not on the same bus. In its gateway role the UMG 801 is the client on RS-485 and polls downstream meters such as a UMG 96-S2 or UMG 103, and a second client cannot share that bus. Read the UMG 801 over Modbus TCP instead.

Do the values include the CT ratio?

Yes for Float and integer values: Janitza's formulary says they already take the configured transformer ratios into account. Values in the short format do not and must be multiplied by the transformer factor. All the measurements in this guide are Float.

Does a Float energy counter in Wh lose resolution?

Yes, gradually. A Float32 holds about seven significant digits: above about 16.8 MWh the counter moves in steps of 2 Wh, above 134 MWh in steps of 16 Wh and above 1.07 GWh in steps of 128 Wh. Store each value as received and calculate consumption over intervals rather than from tiny differences.

Janitza UMG 801 Modbus register map

Compatibility

Compatible with EpiSensor Edge over Modbus TCP or Modbus RTU

The UMG 801 is compatible with EpiSensor Edge over Modbus TCP on either Ethernet port (port 502) and over Modbus RTU on its RS-485 port, read through a ZMB-31 Modbus Interface or a Gateway serial port. Janitza publishes the complete address list with decimal addresses, data types and units, and a formulary that fixes the byte order as big-endian.

UMG 801 base device in its factory physical measurement group mode, with any 800-series current measuring modules, using the Modbus address list 2.053.265.1.a with formulary 2.053.016.1.b (06/2025, from firmware 1.6.2) and user manual 2.053.021.4.a (07/2026, firmware 1.7.3) as a best-effort starting point. Site check: compare the first voltage read with the display, and download the active address list from the device homepage when modules are fitted. Virtual Meter mode generates a different address list and is outside this guide. Read-only monitoring.

Connect it with

Route into Edge

Ethernet Modbus TCP RS-485 through ZMB-31 RS-485 to the Gateway serial port

When the analyser sits on a site network, or its RS-485 port already serves another Modbus client or acts as a gateway

Modbus
Edge
Platforms

Both Ethernet ports take their address from DHCP by default and work independently, so pick the port on the network the Gateway can reach and give it a fixed or reserved address. The Modbus TCP server listens on port 502, which can be changed. If the meter's Modbus whitelist is in use, add the Gateway's address to it. The customer-platform output is optional; Edge remains the local system of record.

For an analyser in a switchboard where a wireless link avoids running a data cable back to the Gateway

Modbus
Wireless
Edge
Platforms

Wire A, B and Data GND from the three-pole RS-485 plug to the ZMB-31, set switch S1 to I when the analyser is at the end of the segment, and match the device address, baud rate and data frame on the Fieldbus screen. The RS-485 port must be in its server role: a UMG 801 acting as an RS-485 gateway already masters that bus. The customer-platform output is optional; Edge remains the local system of record.

When the Gateway sits near the analyser, or several Janitza meters share one wired RS-485 bus

Modbus
Edge
Platforms

Run the devices in line, up to 32 per segment and 1200 m at 38.4 kbit/s, with each meter on its own device address and the same baud rate and data frame throughout. Janitza recommends Unitronic Li2YCY(TP) 2 × 2 × 0.22 cable, not CAT cable, and connecting Data GND as the functional earth. The customer-platform output is optional; Edge remains the local system of record.

Models

Download

Models	Interface	Route into Edge
UMG 801 base device	24 V DC supply; four voltage inputs; current inputs I1 to I4 and I5 to I8 for ../1 A or ../5 A transformers; RS-485 Modbus RTU; Ethernet A and B; four multifunction channels for residual current or temperature	Read measurement group 01 (I1 to I4) from 19012 and measurement group 02 (I5 to I8) from 19200, both with the voltages at 19000, over Modbus TCP or RS-485.
UMG 801 with 800-CT8-A, 800-CT8-LP, 800-CT24 or 800-CT12-SVD-US modules	Current measuring modules and 800-DI14 digital input modules on the JanBus at the back, up to 104 current channels in total (8 on the base device, 96 on modules)	Module measurement groups 01 to 20 start at 19400, 19500 and so on in steps of 100. Which groups exist depends on the modules fitted; take the active list from the device homepage.
UMG 801 in Virtual Meter mode	Channels from the base device and modules regrouped into up to 32 virtual measurement groups; switching mode resets the device to factory settings	The device generates a new address list for this mode. Use that list, not the physical-mode addresses in this guide.

Specifications

The UMG 801 measures two three- or four-wire systems on its own, or eight single channels, against one set of voltage inputs. Current measuring modules plug into the JanBus on its back and add measurement groups, each with its own block in the address list, so the same Modbus layout repeats at fixed steps. Janitza ships it in the physical measurement group mode that this guide uses.^1, 2

Firmware and documents: User manual 2.053.021.4.a (07/2026) describes firmware 1.7.3. The address list and formulary apply from firmware 1.6.2.^1, 2
Supply: 24 V DC PELV, ±10 %; up to 4 W, or 14 W with modules.³
Voltage: Three-phase four-wire systems up to 480 V L-N / 830 V L-L (IEC); measuring range up to 720 V L-N; 1000 V CAT III up to 2000 m; fundamental 40 to 70 Hz.³
Current: Eight channels for ../1 A or ../5 A transformers, as two systems (L1, L2, L3, N) or single channels; 0.005 to 6 A. Up to 104 channels with modules.^1, 3
Accuracy: Active energy class 0.2S (IEC 62053-22) with ../5 A and 0.5S with ../1 A transformers; voltage and current 0.2 and frequency 0.05 to IEC 61557-12.^1, 3
RS-485: Three-pole plug with A, B and C (Data GND); Modbus RTU server or gateway; 9600 to 115200 bit/s. Defaults: device address 1, 115200 bit/s, 1 stop bit, no parity. Termination switch S1.¹
Ethernet: Two RJ45 ports used separately, DHCP by default. Modbus TCP and Modbus UDP on port 502 (changeable), OPC UA on 4840, HTTP on 80.^1, 3
Other inputs and outputs: Four digital inputs, four digital outputs, one 0/4 to 20 mA analog output and four multifunction channels for residual current or temperature.³
Mounting: 35 mm DIN rail, 8 HP; 144 × 90 × 76 mm; 420 g.³
Environment: -10 to +55 °C; 5 to 95 % RH without condensation; IP20; pollution degree 2; weather-protected, stationary use.³

Interface

Documented measurements and integration boundaries for UMG 801.

Addresses are decimal and go on the wire as printed: 19000 is sent as 4A 38. Read with FC03; the UMG 801 also answers FC04. Every measurement is a two-register IEEE-754 Float, big-endian, high byte and high word first.
Voltage L1-N, L2-N and L3-N at 19000, 19002 and 19004; L1-L2, L2-L3 and L3-L1 at 19006, 19008 and 19010: Float, V.
Measurement group 01 (inputs I1 to I4): current I1 to I4 at 19012, 19014, 19016 and 19018 (A); active power P1 to P3 at 19020, 19022 and 19024 and the sum P1+P2+P3 at 19026 (W).
Group 01 apparent power S1 to S3 and sum at 19028 to 19034 (VA), fundamental reactive power Q1 to Q3 and sum at 19036 to 19042 (var), cos φ for L1 to L3 at 19044 to 19048, frequency at 19050 (Hz) and rotary field at 19052 (1 right, 0 none, -1 left).
Group 01 energy, Float in Wh: total active energy W1..W3 at 19060, purchased tariff 1 at 19068 and supplied at 19076, with per-phase purchased values at 19062 to 19066 and supplied values at 19070 to 19074. Apparent energy at 19084 (VAh); reactive energy at 19092, inductive at 19100 and capacitive at 19108 (varh).
Measurement group 02 (inputs I5 to I8) repeats the group 01 layout from 19200: current at 19200 to 19206, total active power at 19214, total active energy at 19244, purchased tariff 1 at 19252 and supplied at 19260. It shares the voltages at 19000 to 19010.
Module measurement groups 01 to 20 use the same layout at 19400, 19500 and onwards in steps of 100, up to 21300: current from the start address, total active power at +14 and total active energy at +44.
Average values over the interval set in GridVis (10 minutes by default) start at 5000: average voltage L1-N at 5000 and average sum active power of I1 to I4 at 5030. Minimum values follow from 8000.
Identity: device name at 4100 (string), firmware version at 4132 (string), state at 4168 (UInt16, 3 = operating) and serial number at 4174 (UInt64). Fitted modules report from 4178.
Float and integer values already include the configured current and voltage transformer ratios; the few values marked short do not. The registers update every 200 ms.
The list marks one register writable, 21444, which starts a new maximum-average interval, and the UMG 801 accepts FC06, FC16 and FC23 writes. Keep them out of the polling configuration.

Assessment

UMG 801 base device in its factory physical measurement group mode, with any 800-series current measuring modules, using the Modbus address list 2.053.265.1.a with formulary 2.053.016.1.b (06/2025, from firmware 1.6.2) and user manual 2.053.021.4.a (07/2026, firmware 1.7.3) as a best-effort starting point. Site check: compare the first voltage read with the display, and download the active address list from the device homepage when modules are fitted. Virtual Meter mode generates a different address list and is outside this guide. Read-only monitoring.

InteroperabilityWell supported: Janitza publishes every address with its format, unit and read or write flag, fixes the byte order in the formulary and documents Modbus TCP, Modbus UDP and Modbus RTU server functions. The device homepage exports the active list for the installed module topology.^1, 2
AccuracyWell supported: Class 0.2S active energy with ../5 A transformers (0.5S with ../1 A), per-phase and total power, separate purchased and supplied energy, and Float values that already include the transformer ratios. System accuracy still depends on the external transformers.^2, 3
SecuritySupported with conditions: The display has a PIN, the homepage a password, and a whitelist can restrict which devices reach Modbus port 502 over Ethernet. Modbus itself has no authentication or encryption and the meter accepts writes, so keep it on a protected network segment.¹
ReliabilitySupported with conditions: Configuration is saved within one or two seconds, while energy, minimum, maximum and average values are saved at least every five minutes, and a CR2032 battery keeps the clock. The meter needs a 24 V DC PELV supply within ±10 %. Treat failed polls as missing data.^1, 3
RuggednessSupported with conditions: Rated -10 to +55 °C, IP20 and IK07 for weather-protected, stationary installation in a cabinet, with 1000 V CAT III voltage inputs up to 2000 m.³
ScalabilitySupported with conditions: One base device reaches 104 current channels with modules and serves Modbus over two Ethernet ports and RS-485, with up to 32 devices per RS-485 segment. Janitza warns that a full expansion raises the system load and suggests switching off event and transient recording.^1, 3
LifecycleNot yet assessed: Janitza publishes firmware updates through the device homepage and asks users to keep the firmware current, but states no support period.¹

Setup

Read L1-N voltage from decimal address 19000

The UMG 801 Modbus address list (2.053.265.1.a) gives Voltage L1-N at address 19000, format Float, read-only, unit V, and the formulary (2.053.016.1.b, 06/2025) says the list's addresses return big-endian data. Use that list as the starting point and compare the result with the display.

Request: RS-485: 01 03 4A 38 00 02 53 DE, device address 1, FC03, address 19000 (0x4A38), two registers, RTU CRC. Modbus TCP: 00 01 00 00 00 06 01 03 4A 38 00 02, the same PDU after the MBAP header with unit identifier 1.
Address convention: Janitza's addresses are decimal and go on the wire as printed: 19000 is the zero-based PDU address 0x4A38. A client that numbers registers from one shows it as 19001 (or 419001 in 4x notation). Do not subtract one.
Synthetic response: 01 03 04 43 66 00 00 0F A8: byte count 04, data 43 66 00 00.
Decode: Big-endian, high word first: 0x43660000 as an IEEE-754 Float32 is 230.0 V. No multiplier applies, and the voltage transformer ratio is already included.
Off by one: A read that starts at 19001 pairs the low word of L1 (00 00) with the high word of L2, for example 43 6A at 234 V. 0x0000436A decodes to about 2.4 × 10⁻⁴¹, so a tiny or nonsensical value points to the address convention, not the meter.
Acceptance: Keep the point when it agrees with L1 voltage on the display at the same time. If it does not, check the device address or unit identifier, the data frame and the address convention before adding more points.

Acceptance: The response bytes are a synthetic decoder check, not a captured reply from a UMG 801. A real reply must agree with the display before current, power and energy points are enabled.

Record the firmware, mode and modules
Note the firmware version and any fitted modules from the display or device homepage, and confirm the meter is in the physical measurement group mode it ships with. Virtual Meter mode uses a different address list.
Choose the connection
For Modbus TCP, give Ethernet A or B a fixed or reserved address and check port 502 and the Modbus whitelist. For RS-485, read the device address, baud rate and data frame from Configuration > Fieldbus (defaults 1, 115200 bit/s, 1 stop bit, no parity) and enter the same values in the client.
Take the active address list
On the device homepage, open the Modbus address list and download the complete list as CSV. With modules fitted it shows exactly which measurement groups this meter has.
Make one voltage read
Send FC03 to address 19000 for two registers and decode the Float big-endian, as in the worked read below. Compare the result with L1 voltage on the display.
Add the points you need
Add current, power and energy from each measurement group. Read purchased and supplied energy separately where the site can export, and keep FC06, FC16 and FC23 writes out of the polling configuration.

Common questions

Is 19000 a one-based register number?: No. Janitza's address lists give the address that goes on the wire, so 19000 is sent as 4A 38. A tool that asks for one-based holding register numbers needs 19001, or 419001. If the first Float read returns a tiny or absurd value, the client is probably one register out.²
Where are current inputs I5 to I8?: In measurement group 02. The list names its four currents I1 to I4 again, starting at 19200, and repeats the group 01 layout: total active power at 19214 and total active energy at 19244. Both groups share the voltages at 19000 to 19010.^1, 2
How do I find the addresses for current measuring modules?: Each module measurement group has a 100-register block from 19400 upwards in the published list, but which blocks exist depends on the modules fitted. The device homepage shows the active Modbus address list and downloads it as a CSV file, including the module addresses. Switching to Virtual Meter mode generates a new list.^1, 2
Can Edge read the RS-485 port when the UMG 801 is a Modbus gateway?: Not on the same bus. In its gateway role the UMG 801 is the client on RS-485 and polls downstream meters such as a UMG 96-S2 or UMG 103, and a second client cannot share that bus. Read the UMG 801 over Modbus TCP instead.^1, 3
Do the values include the CT ratio?: Yes for Float and integer values: Janitza's formulary says they already take the configured transformer ratios into account. Values in the short format do not and must be multiplied by the transformer factor. All the measurements in this guide are Float.²
Does a Float energy counter in Wh lose resolution?: Yes, gradually. A Float32 holds about seven significant digits: above about 16.8 MWh the counter moves in steps of 2 Wh, above 134 MWh in steps of 16 Wh and above 1.07 GWh in steps of 128 Wh. Store each value as received and calculate consumption over intervals rather than from tiny differences.²

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Janitza UMG 801

Compatibility

Connect it with

Models

Specifications

Interface

Assessment

Setup

Read L1-N voltage from decimal address 19000

Common questions

Sources

Further reading

Janitza UMG 801

Compatibility

Connect it with

Models

Specifications

Interface

Assessment

Setup

Read L1-N voltage from decimal address 19000

Common questions

Related devices

Sources

Further reading

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