In FlexRay, the Electrical Physical Layer(EPL) forms the physical signal level on which the pin assignment of the signals, the voltages used, the switching thresholds and the temporal signal characteristics are defined.
The physical signal level is used to transmit data at data rates of 10 Mbit/s between the electronic control units( ECU) in time-related networks in automotive technology. Twin wires are used as the transmission medium. The signaling on the FlexRay bus is derived from the voltage difference between the two cores of the twin wire. The topology can vary between a point-to-point connection, a bus or a star topology.
The specifications for the Electrical Physical Layer are defined in ISO 17458-4 from 2013.