Redundant Network Access Points

Offering a fault-tolerant system solution for smooth and thus delay-free redundancy in industrial Ethernet networks, the Scalance X-200RNA (Redundant Network Access) network access points from Siemens Industry Automation Division are based on the parallel redundancy protocol (PRP) in accordance with the IEC 62439-3 standard. They connect one or two network segments or data terminals without PRP functionality over two parallel networks without delay. An access point duplicates the transmitter’s message and feeds a copy into each of the connected networks. The two LANs can have different structures such as star, ring or tree. At the receiver end, the second access point passes on the first message frame which arrives to the addressees. The message frame which arrives subsequently from the other LAN is discarded. The two separate networks and the PRP procedure guarantee secure and punctual transmission. A reconfiguration time as required by other redundancy procedures using only one physical network is therefore superfluous. Typical areas of application for fault-tolerant redundant connections can be found in the energy sector as well as in process automation, for example in the pharmaceutical or chemical industries. The new access points are offered as Scalance X204RNA in a plastic enclosure with four electric RJ45 ports as well as Scalance X204RNA EEC (Enhanced Environmental Conditions) in a metal enclosure with two electric ports and two electric/optical combined ports for SFP (Small Form-Factor Pluggable) transceivers and wide-range power supplies. Various information for network diagnostics is available via SNMP. Also offered, the Softnet-IE RNA software package can be used for linking PCs at low cost into redundant, parallel network topologies based on PRP without additional programming overheads. Using the software, a computer can establish the same smooth redundancy connection over two LAN networks as the Scalance X-200RNA network access points.