Both registers return zero even though the system is live. Why?

The Powerdog may not have Modbus TCP enabled. Check the device configuration interface and confirm that the Modbus server is active. Also verify that the unit ID configured in the ModbusCloud portal matches the slave ID set on the Powerdog, as a mismatch silently returns zeros on many devices.

Register values look unexpectedly large or wrong. What is the cause?

Both power_a and power_b are int32 types spanning two consecutive 16-bit registers. If your polling tool or gateway reads only a single 16-bit word instead of two consecutive registers (four bytes), the result will be incorrect. Confirm that the template is configured to read two registers per channel and that byte order is big-endian, which is standard for Modbus.

The gateway connects but register 40026 always times out. Register 40002 is fine.

Some Powerdog firmware versions may not populate register 40026 unless a specific operational mode or metering option is active. Check that the hardware configuration includes a second power channel and that the firmware version in use supports reading at address 40026. Consult the ecodata documentation for your specific device revision.

How do I tell whether a power reading represents import or export?

The registers are typed as int32, meaning values are signed. A positive value typically indicates power drawn from the grid (import), and a negative value indicates power fed into the grid (export). Confirm the sign convention with the ecodata documentation for your specific Powerdog firmware, as conventions can vary between device generations.

Free Modbus template: Powerdog Powerdog (grid)

The Powerdog is an energy management and PV monitoring system developed by ecodata solutions GmbH, deployed at grid connection points on solar installations. This template reads two signed 32-bit active power values over Modbus TCP: power_a (register 40026) and power_b (register 40002), representing the two active power channels at the grid meter interface. Both registers use function code 3 and carry no unit scaling in the register definition, so raw integer values correspond directly to watts. Connecting the Powerdog to ModbusCloud gives installers live and historical visibility into grid power flows without additional hardware.

Name	Address	Function	Type	Unit	Access
power_a Active power reading, channel A, at the grid connection point.	40026	FC03	int32	W	R
power_b Active power reading, channel B, at the grid connection point.	40002	FC03	int32	W	R