Measure current and consumption
The state of this meter can be read in 3 ways:


Pulse, this is very easy to implement. But depending on the stability of the hardware u can miss pulses leading to inaccurate values. In this way u have to calculate the meter value yourself.
RS485, this is a communication bus not default on arduino. But given this link https://arduino-info.wikispaces.com/RS485-Modules i think it is doable but not easy. This will read the value from the meter.
M-Bus: There is special hardware needed to interact with it. This is the industry standard of doing it. It's not cheap. But u can link many meters together. This will read the value from the meter.


Depending on your time/knowledge/other requirements u have to make a chose what way your going to use.