The relay communication card has an X3 Ethernet port which is an interlink port that can be used to connect other relays or devices to the HSR or PRP station bus. This port works as a redundancy box (RedBox) port for other devices. It also supports IEEE 1588 making it possible to connect the PTP grandmaster clock to the station bus using it. Additionally, single attached nodes connected to the interlink port can receive 1588 time synchronization over this port.