CarloGavazzi EM100
The CarloGavazzi EM100 is a single-phase energy analyser designed for DIN-rail mounting in residential, commercial, and light-industrial metering applications. It communicates over RS485 using Modbus RTU and exposes six key electrical measurements: voltage, current, active power, apparent power, reactive power, and grid frequency. This ModbusCloud template maps those registers directly, giving your portal a complete real-time picture of single-phase load behaviour with no manual configuration required. Use it in any installation where a compact, read-only power quality snapshot is needed alongside other RS485 devices on a shared bus.
- Protocol
- Modbus RTU
- Connection
- RS485
- Registers
- 6, read only
- Brand
- CarloGavazzi
- Last updated
Registers (6)
6 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| voltage | V | Read | |||
| current | A | Read | |||
| active_power | W | Read | |||
| apparent_power | VA | Read | |||
| reactive_power | var | Read | |||
| frequency | Hz | Read |
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Use cases
- Monitor instantaneous active power to verify that a circuit load stays within its rated capacity.
- Track reactive power alongside apparent power to identify poor power-factor loads needing correction.
- Alert on voltage deviations at the meter to detect upstream supply quality problems early.
- Compare frequency readings against nominal 50 Hz to spot grid instability at a specific site.
- Log current over time on a shared RS485 bus to audit individual circuit consumption across multiple meters.
Installation
On the EM100, enter the programming menu and set the Modbus RTU address, baud rate, and parity under the communication parameters section; note the chosen unit ID.
Wire the RS485 A and B terminals of the EM100 to the corresponding terminals of the ModbusCloud Gateway using a twisted-pair cable, and fit a 120-ohm termination resistor at each end of the bus if this device is last on the chain.
In the ModbusCloud portal, add a new Gateway, select the RTU transport, then import the CarloGavazzi EM100 template and assign the unit ID that matches the address set on the meter.
Open the live register view and spot-check the voltage and frequency values against the meter display to confirm that polling is working and byte order is correct.
Things to watch for
All register values read as zero or max. What is wrong?
The EM100 uses big-endian (MSB-first) byte order within each 16-bit word, and 32-bit values span two consecutive registers with the high word first. If your gateway byte-swap or word-swap settings do not match this, every int32 register will decode incorrectly. Verify the word order setting in the ModbusCloud Gateway RTU configuration.
The gateway connects but no readings appear in the portal.
Confirm that the Modbus RTU slave address on the EM100 matches the unit ID entered in the portal. Also check that baud rate and parity on the meter (typically 9600 baud, even parity) match the Gateway serial port settings. A mismatch on either will produce silence with no CRC errors.
Values are noisy or the meter drops off the bus intermittently.
RS485 buses require proper termination. Place a 120-ohm resistor between the A and B lines at the far end of the bus, and connect the cable shield to ground at the master side only. On the EM100 specifically, connect terminal A- to terminal T on the last device on the bus to activate the built-in termination.
Function code 4 returns an exception but function code 3 works. Is that normal?
Yes, this is expected behaviour. The EM100 register map is addressed via function code 04 (Read Input Registers), but according to the Carlo Gavazzi communication protocol, functions 03h and 04h have exactly the same effect and can be used interchangeably. The template uses FC4, which is the primary mapping. Switching to FC3 at the same physical addresses also works.
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