The instrument has three different connections: power supply (+24 Vdc), 4 … 20 mA current output, and an Ethernet connection for digital data acquisition and configuration.
These connections are grouped into two connectors so that one of the connectors carries both the power supply and the current output. The other connector is an Ethernet connection.
Both connections use the industrial M12 connector. The Ethernet connector has the industry standard M12-Ethernet pin-out. The power supply and current output use an A-coded M12 male on the instrument side. The Ethernet connection uses a D-coded female connector on the instrument side.
For the wiring details, see Refractometer wiring.