A communications interface apparatus for Ethernet communications, the apparatus comprising: a physical layer interface configured to receive first data from an external device and output the received first data; wherein the first data is Ethernet data received from the external device; a medium access control, MAC, layer interface configured to receive the first data output via the physical layer interface, transmit the received first data to an upper layer, and receive second data in response to the transmitted first data, wherein the second data is obtained by processing the first data in the upper layer; and a relay configured to receive the first data output via the physical layer interface and create third data, wherein the third data is obtained by processing the first data in the relay, characterized in, that the relay is configured to store processing condition information corresponding to the first data received from the external device, wherein the processing condition information is set based on at least one of a destination address, a source address, a type, a length, and a transmission time variable of the received first data and defines a condition to determine whether and with which content the third data is created, to create the third data, based on the processing condition information, corresponding to the received first data upon receiving the first data via the physical layer interface, and to decide when to transmit the third data based on the transmission time variable of the received first data; and that the MAC layer interface comprises: a receive buffer storing the received first data; a transmit buffer storing the second data transmitted from the upper layer; and a transmission status management unit controlling one transmission of the third data and the second data to the physical layer interface via the transmitting unit, wherein the transmission status management unit is configured to receive the third data from the relay, to check if the second data is being transmitted and to transmit the third data to the physical layer interface when the second data is not transmitted. a physical layer interface configured to receive first data from an external device and output the received first data; wherein the first data is Ethernet data received from the external device; a medium access control, MAC, layer interface configured to receive the first data output via the physical layer interface, transmit the received first data to an upper layer, and receive second data in response to the transmitted first data, wherein the second data is obtained by processing the first data in the upper layer; and a relay configured to receive the first data output via the physical layer interface and create third data, wherein the third data is obtained by processing the first data in the relay, characterized in, that the relay is configured to store processing condition information corresponding to the first data received from the external device, wherein the processing condition information is set based on at least one of a destination address, a source address, a type, a length, and a transmission time variable of the received first data and defines a condition to determine whether and with which content the third data is created, to create the third data, based on the processing condition information, corresponding to the received first data upon receiving the first data via the physical layer interface, and to decide when to transmit the third data based on the transmission time variable of the received first data; and that the MAC layer interface comprises: a receive buffer storing the received first data; a transmit buffer storing the second data transmitted from the upper layer; and a transmission status management unit controlling one transmission of the third data and the second data to the physical layer interface via the transmitting unit, wherein the transmission status management unit is configured to receive the third data from the relay, to check if the second data is being transmitted and to transmit the third data to the physical layer interface when the second data is not transmitted.