Reliable Ethernet Networks are gaining acceptance for many Industrial Automation applications. One illustrative example of this evolution, is the adoption by the International Electrotechnical Commission of the High-availability Seamless Redundancy (HSR) Ethernet based protocol and Parallel Redundancy Protocol (PRP) for Power Substations Automation (IEC 61439-3 clauses 4 and 5).
Both protocols offer zero switchover delay time, no-frames lost in case of failure, and strong means for Network Supervision at Layer 2.
HSR provides redundancy by sending packets in both directions through a ring network and discarding the duplicated one on HSR capable reception node. In case of an interruption in the ring, the frame will always be received through the other port.
PRP adapted nodes are connected to two independent Ethernet networks and send the frame over both networks. This grants the reception of the frame through when any of the network fails.
- Network Communications in Power Substation using HSR and PRP -
The figure above shows an example of this new protocols implemented in the automation for a Power Substation. While HSR interconnects Intelligent Electronic Devices (IEDs) in each bay (Intra-Bay communications), PRP is suitable to be used for Station and Inter-Bay Buses, attaching many heterogeneous devices.
As can be depicted in this example, in order to maintain redundancy in the communications, the interconnection between PRP and HSR networks is performed using redundant gateways. Each HSR link is connected to each PRP LAN using two gateway devices. Thus, a potential ‘Single-Pointof-Failure’ is avoided.
As it has shown in this scenario, the combination of industrial protocols is increasing in complexity and variety. The need for flexibility of these emerging Ethernet based protocols makes FPGA and reconfigurable devices in general, the best candidates to implement network devices able to combine multiple protocols. FPGAs, powered by the proper IP Core provide:
- Hardware processing capabilities to achieve low switching latency times
- Flexibility enough to adapt the design to specific customer requirements
- Protocol updates supported by hardware and complex combinations (eg. HSR and IEEE 1588)
With the idea of meeting this need, SoC-e is positioned in the forefront of the market, offering it’s HSR/PRP Switch IP Core. This, combined with the new generation of cost-affordable System-on-Chip devices like Xilinx Zynq devices (double core Cortex-ARM9 and 28nm reconfigurable logic on a single chip) results in a powerful platform that will set the course of this market.