FENECON Modbus-API (pv)
The FENECON Modbus-API is the built-in Modbus TCP interface of FENECON energy management systems (FEMS), running on FENECON Home, Commercial, and similar PV-plus-storage installations. This template targets the PV production data path and reads two registers over Modbus TCP: instantaneous production active power at address 327 and cumulative produced energy at address 367. Both values are aggregated by FEMS across all connected PV sources, giving installers and asset managers a single, reliable data point for site-level solar output without needing per-inverter polling.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 2, read only
- Brand
- FENECON
- Compatible models
- Modbus-API
- Last updated
Registers (2)
2 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| energy | Wh | Read |
Loading registers…
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Use cases
- Monitor instantaneous PV production power to verify the system is generating expected output during daylight hours.
- Track cumulative PV energy to calculate daily, monthly, and annual production totals in your ModbusCloud dashboard.
- Alert on production power dropping to zero during expected generation hours to detect inverter or communication faults.
- Compare logged PV production energy against utility meter exports to spot self-consumption or metering discrepancies.
- Report historical PV output trends to building owners for performance reviews and yield verification.
Installation
Verify that the FEMS Modbus TCP read-access interface is active on the FENECON system: open Online Monitoring, go to Settings, open the system profile, and confirm the ctrlApiModbusTcp component is listed and enabled.
Connect the ModbusCloud Gateway to the same LAN as the FENECON FEMS unit, ensuring IP reachability between the Gateway and the FEMS IP address on TCP port 502.
In the ModbusCloud portal, add the Gateway, import the FENECON Modbus-API (pv) template, and set the unit ID to 1 and the host to the FEMS IP address.
Spot-check register 327 in the portal's live register view: the value should match the current PV production power shown in FENECON Online Monitoring.
Things to watch for
Register 327 reads zero even when PV is producing. Why?
The most common cause is a base-address offset. FENECON documents addresses starting at 0, but some Modbus clients default to base address 1, shifting every register by one position. Confirm your ModbusCloud template uses base address 0 and that no offset is applied in the gateway configuration.
The energy register at address 367 returns an error or garbage. What is wrong?
Address 367 is a float64 value spanning four consecutive 16-bit registers. If your client requests only two registers (as it would for float32), the read will be incomplete or return an exception code. Ensure the template requests four registers starting at address 367 with function code 3.
The Gateway connects to port 502 but no values appear in the portal.
Check that the FEMS is reachable from the Gateway's network segment. FENECON's Modbus TCP interface requires the client to be on the same physical network as the FEMS. Also confirm that no local firewall on the FEMS or a managed switch is blocking port 502.
Values stopped updating after a FEMS firmware upgrade. How do I fix this?
FEMS firmware updates occasionally change component IDs or reset the Modbus app configuration. After upgrading, open Online Monitoring, navigate to Settings, and verify the ctrlApiModbusTcp component is still present and active. Re-enable it in the App Center if it has been deactivated, then restart polling in the ModbusCloud portal.
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