Carlo Gavazzi EM340

Use cases

• Monitor per-phase voltage, current, and power on a live dashboard to detect load imbalances.
• Track imported and exported energy totals to quantify PV self-consumption for your customer.
• Create an alert when power factor on any phase drops below a defined threshold for more than five minutes.
• Generate monthly energy reports comparing grid import versus solar export across multiple sites.
• Trigger a partial energy counter reset remotely from the cloud after a billing period ends.
• Verify correct CT and wiring polarity by comparing per-phase power readings immediately after installation.

Installation

1. 1Wire the EM340 current and voltage inputs according to the Carlo Gavazzi installation manual, ensuring correct phase sequence and CT orientation.
2. 2Connect the RS-485 A and B terminals of the EM340 to the corresponding terminals on the ModbusCloud gateway (MCG or MLP series), and add a 120 ohm termination resistor if the meter is at the end of the bus.
3. 3Set the Modbus slave address on the EM340 front panel and confirm the baud rate is 9600, matching the gateway configuration.
4. 4In the ModbusCloud platform, add a new device and select the Carlo Gavazzi EM340 template from the template library.
5. 5Enter the slave address configured on the meter and assign the device to the correct gateway in your project.
6. 6Verify that live readings appear on the dashboard, checking that voltage and current values match expected values to confirm correct wiring.

Things to watch for

01

The gateway reads zero or incorrect values for power registers. What should I check?

Confirm that the RS-485 wiring polarity (A and B) is not swapped between the meter and the gateway. Also verify that the slave address in ModbusCloud matches the address configured on the EM340 display.

02

Do I need to change the default baud rate on the EM340?

No. The template is configured for 9600 baud, which is the factory default of the EM340. Make sure the ModbusCloud gateway serial port is also set to 9600, 8N1.

03

Why do exported energy registers show zero even though the PV system is feeding in?

Check that the CTs are installed in the correct orientation. Reversed CTs will cause export energy to be counted as import. The Carlo Gavazzi manual specifies the correct CT direction relative to grid flow.

04

What data types are used in this template?

Measurement registers use int32 or uint32 data types spanning two consecutive Modbus registers. The Partial Reset and Total Reset registers are write-only uint16 values.

Registers (43)

41 read / 3 write

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