BControl EM300
The BControl EM300 is a three-phase bidirectional energy meter designed for industrial and commercial grid monitoring, typically deployed at the grid connection point of PV systems, battery storage installations, and multi-circuit distribution boards. This template reads the meter over Modbus TCP, covering total and per-phase active power (import and export), reactive power (inductive and capacitive), per-phase voltage and current, grid frequency, and cumulative energy totals for both consumption and production. Installers gain a complete real-time picture of grid interaction without additional hardware.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 31, read only
- Brand
- BControl
- Last updated
Registers (31)
31 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| active_power_pos | W | Read | |||
| active_power_neg | W | Read | |||
| reactive_power_pos | var | Read | |||
| reactive_power_neg | var | Read | |||
| frequency | Hz | Read | |||
| active_power_l1_pos | W | Read | |||
| active_power_l1_neg | W | Read | |||
| reactive_power_l1_pos | var | Read | |||
| reactive_power_l1_neg | var | Read | |||
| current_l1 | A | Read | |||
| voltage_l1 | V | Read | |||
| active_power_l2_pos | W | Read | |||
| active_power_l2_neg | W | Read | |||
| reactive_power_l2_pos | var | Read | |||
| reactive_power_l2_neg | var | Read | |||
| current_l2 | A | Read | |||
| voltage_l2 | V | Read | |||
| active_power_l3_pos | W | Read | |||
| active_power_l3_neg | W | Read | |||
| reactive_power_l3_pos | var | Read | |||
| reactive_power_l3_neg | var | Read | |||
| current_l3 | A | Read | |||
| voltage_l3 | V | Read | |||
| active_consumption_energy | Wh | Read | |||
| active_production_energy | Wh | Read | |||
| active_consumption_energy_l1 | Wh | Read | |||
| active_production_energy_l1 | Wh | Read | |||
| active_consumption_energy_l2 | Wh | Read | |||
| active_production_energy_l2 | Wh | Read | |||
| active_consumption_energy_l3 | Wh | Read | |||
| active_production_energy_l3 | Wh | Read |
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Monitor total active power import and export in real time to verify PV system feed-in behaviour.
- Track per-phase voltage and current on L1, L2, and L3 to detect phase imbalance in distribution boards.
- Compare cumulative consumption and production energy totals to calculate net energy balance over billing periods.
- Alert on reactive power excursions on any phase to identify power-factor issues from inductive loads.
- Verify grid frequency readings to confirm stable utility supply at a site during commissioning.
Installation
Enable Modbus TCP on the BControl EM300 via its built-in web interface: log in with the device IP, navigate to the communication or Modbus section, and activate the Modbus TCP slave.
Connect the EM300 to the same Ethernet LAN segment as the ModbusCloud Gateway, and confirm the meter's IP address is reachable by pinging it from a laptop on the same network.
In the ModbusCloud portal, add the Gateway, then import the BControl EM300 template and enter the meter's IP address and Modbus unit ID (default is 1) in the device configuration.
Spot-check the connection by reading register address 26 (frequency): a stable value near 50 Hz confirms the Gateway is polling the meter correctly.
Things to watch for
All power registers read zero even though the meter is live. Why?
Modbus TCP slave mode must be explicitly enabled in the EM300 web interface. If it was never activated, the device will accept TCP connections but return zeroed holding registers. Log in to the meter's web UI, navigate to the communication settings, enable Modbus TCP, and save. Then restart the poll in the ModbusCloud portal.
Power values appear but seem roughly half the expected figure. What is wrong?
The EM300 reports active and reactive power as unsigned 32-bit integers split into positive (import) and negative (export) registers. If you are summing them without accounting for direction, the net result will be incorrect. Use active_power_pos minus active_power_neg to derive net active power in your dashboard formula.
The Gateway connects but register reads time out intermittently. What should I check?
The EM300 supports a limited number of simultaneous Modbus TCP connections. If other systems (inverters, building controllers) are also polling the meter, connection slots may be exhausted. Reduce the number of concurrent Modbus clients or increase the poll interval in the ModbusCloud portal to avoid contention.
Energy totalizer registers (addresses 512 and above) return unexpected large values. Is scaling off?
The cumulative energy registers are 64-bit unsigned integers (uint64) spread across four consecutive 16-bit Modbus words in big-endian word order. Ensure your Modbus client assembles all four words with the most-significant word first. Misassembly of word order is the most common cause of implausible energy totals.
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