The Loxone Modbus Extension - without a Template 

Thanks for sharing. For long-term accurate readings of total consumption, I would probably use the registers from the "Total energy accumulator" section instead. Active Power becomes less accurate with lower poll frequency because it does not know when, if, or how consumption changed between readings. Also, there is a cheaper option: you can connect a pulse consumption meter to a digital input. It can be two or three times cheaper, and you don't need a Modbus extension. The downside is that you need a digital input for each meter, and you can only read consumption.

can you use Modbus rs light switch? as they are way cheaper?