Register 40002 returns zero during the day. What is wrong?

Confirm that the Modbus TCP server is enabled in the Powerdog web interface and that at least one inverter is actively communicating with the Powerdog. If the Powerdog has lost contact with its upstream inverter, it may report zero rather than an error. Check the Powerdog's own monitoring portal to see whether inverter data is live.

The gateway connects but no values appear in the portal. What now?

Verify the IP address, port (502), and unit ID configured in your ModbusCloud portal match the Powerdog's actual settings. Firewalls or VLAN segmentation between the Gateway and the Powerdog are a common cause of silent connection failures. Test with a Modbus TCP tool from the same network segment to rule out network issues.

The power value is negative or unexpectedly large. Is the scaling correct?

Register 40002 is typed as a signed 32-bit integer (int32). Ensure the ModbusCloud template is configured for int32 and not uint16 or uint32, which would misinterpret the two-register value. A negative reading could also indicate a firmware or configuration mismatch on the Powerdog side; verify the register content against the Powerdog's local dashboard.

Readings drop out intermittently every few minutes. What causes this?

The Powerdog's Modbus TCP server has a limited number of simultaneous connections. If another system (such as a home automation controller or a direct-marketing gateway) is already polling the device, the ModbusCloud Gateway may be refused or dropped. Reduce polling frequency or check how many active Modbus clients are connected to the Powerdog at the same time.

Free Modbus template: Powerdog Powerdog (pv)

Name: Powerdog Powerdog (pv)
Brand: Powerdog
SKU: 8282d024-58e1-446a-8deb-6819c22d7376

The Powerdog is a PV monitoring and energy management data logger made by ecodata GmbH. Installed at the site, it aggregates data from connected inverters and exposes values over Modbus TCP. This template reads the instantaneous PV production power from holding register 40002, giving your ModbusCloud portal a live view of solar generation output. With this single register polled by the ModbusCloud Gateway, you can trend production, trigger alerts on unexpected drops, and verify that the installation is generating as expected.