This part of IEC 61375 specifies rules for the data exchange between consists in trains. The aggregation of these rules defines the TCN communication profile.

The objective of the communication profile is to ensure interoperability between consists of the said trains with respect to the exchange of information. For this it defines all those items which are necessary for communication interoperability:

As a restriction, this communication profile is adhered to the Ethernet Train Backbone (ETB) technology as defined in IEC 61375‑2‑5. Towards the consistnetworks, a more abstract interface is defined which does not restrict the appliance of any consistnetwork technology as for instance MVB (IEC 61375‑3‑1), CANOpen (IEC 61375‑3‑3) or ECN (IEC 61375‑3‑4).

It is not within the scope of the communication profile to define application data content and its meaning (e.g. syntax and semantics). This is within the responsibility of the application profiles. Namely two application profiles are explicitly supported as shown in Figure 1: the TCMS application profile as defined in IEC 61375‑2‑4, and the onboard multimedia and telematic services (OMTS) related profiles as defined in the IEC 62580 series.