Siemens has expanded its portfolio for RNA (Redundant Network Access) components with a communications processor which facilitates high-availability connection of the Simatic S7-400 controller to networks. Simatic CP 443-1 RNA utilizes the Parallel Redundancy Protocol (PRP) in accord-ance with the IEC 62439-3 standard. The communications processor features two RJ45 ports for connecting two parallel Industrial Ethernet networks. The CP 443-1 RNA doubles the frame and feeds it into the two connected networks. The network access point on the receiver side relays the first incoming frame to the addressees and discards the later frame. The device is designed among other things for use in process industry plants and power generation and distribution applications. The new communications processor supports open communication via TCP/IP, UDP and the ISO transport protocol as well as S7, PG/OP and S7 H communication for S7-400 H systems. Data can be transmitted in full or half-duplex mode in bandwidths of 10 or 100 Mbit/s. The user can view diagnostics information via SNMP, STEP 7 or the Web server of the communications processor. In addition the CP 443-1 RNA has a third Ethernet interface with restricted functional scope. On the basis of the ISO transport protocol, the port supports S7 communication services only, all others are deactivated. Fewer functions mean less testing overhead and lower qualification costs.