This part of IEC 62056 describes three profiles for local bus data exchange with stations either energized or not. For non-energized stations, the bus supplies energy for data exchange. Three different profiles are supported: • base profile: this three-layer profile provides remote communication services; NOTE – This first profile has been published in IEC 61142:1993 and became known as the Euridis standard. • profile with DLMS: this profile allows using DLMS services as specified in IEC 61334-4-41; NOTE – This second profile has been published in IEC 62056-31 Ed. 1.0:1999; • profile with DLMS/COSEM: this profile allows using the DLMS/COSEM Application layer and the COSEM object model as specified in IEC 62056-5-3 Ed. 1.0:— and in IEC 62056- 6-2 Ed. 1.0:— respectively. The three profiles use the same physical layer and they are fully compatible, meaning that devices implementing any of these profiles can be operated on the same bus. The transmission medium is twisted pair using carrier signalling and it is known as the Euridis Bus.