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.

Free Modbus template: 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.

Name	Address	Function	Type	Unit	Access
power Instantaneous total PV production active power, in watts.	327	FC04	float32	W	R
energy Cumulative PV energy produced, float64 spanning four registers.	367	FC03	float64	Wh	R

FENECON Modbus-API (pv)

Overview

Use cases

Installation

Things to watch for

Registers (2)

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