Fenecon Mini GridMeter
The Fenecon Mini GridMeter is the integrated grid-metering component of the Fenecon Mini home energy storage system, managed by the FEMS (FENECON Energy Management System). It runs over Modbus TCP and exposes a single register: active power at the grid connection point (address 4004, int16, watts). Positive values indicate power drawn from the grid; negative values indicate export to the grid. Connecting the ModbusCloud Gateway to the same local network as the FEMS box lets your portal continuously record grid import and export flows, giving installers a reliable, time-stamped power baseline for auditing self-consumption performance.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 1, read only
- Brand
- Fenecon
- Last updated
Registers (1)
1 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| active_power | W | Read |
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Use cases
- Monitor real-time grid import and export power to verify the Fenecon Mini system is performing as commissioned.
- Alert on sustained grid import above a threshold to detect battery or inverter faults during daylight hours.
- Track daily grid-import trends over weeks to identify changes in household consumption patterns.
- Compare grid active power against expected zero-export targets to confirm zero-feed-in configuration is effective.
- Report historical grid power data for energy audits or utility compliance submissions at residential sites.
Installation
Confirm Modbus TCP read access is enabled on the FEMS box: open the FEMS online monitoring portal, navigate to Settings, then the system profile, and verify or install the FEMS App Modbus/TCP read access (the read interface is pre-installed by default).
Connect the ModbusCloud Gateway to the same local Ethernet network as the FEMS box so the Gateway can reach the FEMS IP address on TCP port 502.
In your ModbusCloud portal, add the Gateway, import the Fenecon Mini GridMeter template, and set the Modbus unit ID to match the unit ID configured in the FEMS Modbus settings (check under the system profile in the FEMS online monitoring for the assigned slave ID).
Verify the connection by checking that register 4004 returns a live signed integer value in watts; a reading of zero during a known grid-import period indicates a wiring or unit ID mismatch.
Things to watch for
Register 4004 always returns zero even when the system is active. What is wrong?
A zero reading most often means the Modbus TCP read interface is not active on the FEMS box. Open the FEMS online monitoring, go to Settings and the system profile, open the Modbus/TCP component, and confirm the read-access app is installed and enabled. Also verify the FEMS IP address and TCP port 502 are reachable from the Gateway.
The Gateway connects but the active power value looks wrong or inverted. Why?
The register is a signed int16 value in watts. Positive means grid import; negative means grid export. If the sign appears inverted relative to your metering convention, check the physical current-transformer orientation on the Fenecon Mini installation. Do not negate values in the portal; resolve polarity at the hardware level.
No Modbus TCP connection can be established to the FEMS box at all.
The device accessing the FEMS must be on the same physical local network as the FEMS box; TCP port 502 is not routed through the internet. Confirm the Gateway and FEMS are on the same LAN segment, check for firewall or VLAN rules blocking port 502, and verify the IP address entered in the portal matches the current FEMS address.
The FEMS firmware was recently updated and Modbus readings stopped. What changed?
FEMS firmware updates have occasionally changed register accessibility or required the Modbus/TCP app to be re-activated. After an update, log into the FEMS online monitoring, open the App Center, and confirm the Modbus/TCP read-access app is still installed and listed as active. Reconnect the Gateway once the app is confirmed running.
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