Circutor CEM-C31

Use cases

• Monitor three-phase voltage, current, and power factor on a live cloud dashboard for each customer site.
• Track total and partial active energy consumption to support billing or energy audits remotely.
• Create an alert when current on any phase exceeds a defined threshold for more than five minutes.
• Reset partial energy counters remotely at the start of a new billing period using the partial reset command.
• Compare reactive energy values across phases to identify power quality issues in commercial buildings.
• Generate historical energy reports per site to advise customers on consumption reduction strategies.

Installation

1. 1Wire the RS-485 A and B terminals of the Circutor CEM-C31 to the corresponding RS-485 port on the ModbusCloud gateway (MCG or MLP series).
2. 2Ensure the CEM-C31 is configured with Modbus RTU enabled, baud rate set to 9600, and a unique slave address on the bus.
3. 3Verify correct RS-485 bus termination if the meter is the last device on the daisy chain.
4. 4Import the Circutor CEM-C31 template in the ModbusCloud platform and assign it to your gateway.
5. 5Set the Modbus slave address in the template configuration to match the address configured on the meter.
6. 6Confirm live data appears on the dashboard by checking voltage and current readings against expected values.

Things to watch for

01

I see zero values for voltage and current but energy registers read correctly. What is wrong?

Instantaneous values like voltage and current are in the 1842+ register range, while energy registers start at low addresses. Verify that your gateway polling configuration covers both address ranges. Some gateways split polling into multiple requests if the address gap is large.

02

What baud rate and parity settings should I use?

The default configuration for the CEM-C31 in this template is 9600 baud. Check the meter display or configuration menu for the parity setting (commonly 8N1 or 8N2) and match it on the gateway serial port settings.

03

Can I connect multiple CEM-C31 meters on the same RS-485 bus?

Yes. Assign each meter a unique Modbus slave address using the meter front panel. Then create a separate device in ModbusCloud for each meter, selecting the same template but with the corresponding slave address.

04

How does the partial reset register work?

Writing the appropriate value to the partial reset register clears the partial energy counters on the meter. This can be triggered from the ModbusCloud platform. The total energy counters are not affected by this command.

Registers (15)

14 read / 1 write

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