Safety relay / DIN rail
Siemens Industrial Communication
DMZ port (DMZ: "demilitarized zone") for secure connection from, for example, remote maintenance modems, laptops, or an additional network. This yellow port protected by firewalls from the red and green ports and can also terminate VPNs.
Redundant protection of automation cells by means of router and firewall redundancy and stand-by linking of the redundant device via the yellow port.