Downlinks are always 8 bytes long and are structured the same way. 3 pairs {address, value} allowing to modify up to
3 ATO registers.
As the Downlinks are necessarily 8 bytes, to record less than 3 registers, you must indicate the same register address
a second time in a row where you want to stop. The module understands when it receives an identical address twice
in a row that it must stop the reconfiguration there.
Example with 3 registers.
Example with 1 register.