Synchronizing NTP Referenced SCADA Systems Interconnected by High-availability Networks

Abstract

Because of its reliability demands, Industry has not previously trusted in commercial Ethernet for data communication, despite being the cheapest option and the de facto standard. Nevertheless, during the last years, some technological innovations have enhanced its safety and predictability so much, that Ethernet has turned into the industrial network. Critical sectors, such as Electric Power, with high-availability and strict timing requirement, have taken advantage of these developments, after having driven them.To allow some other crucial applications to get benefit from these innovations, the next step is providing system integrators with validated and compatible equipment. For this purpose, our paper presents a Smart PCIe card that delivers a common main clock throughout the industrial data network. Our design supports zero-delay recovery sub-standards (HSR and PRP), and autonomously manages Precise-Time-Protocol (PTP or IEEE 1588), for accurate synchronization over Ethernet. Besides, the board integrates a clock protocol gateway, so that legacy systems, not compatible with the PTP reference, can be synchronously attached. As an example, the presented use-case synchronizes a SCADA system by taking the time reference from the Windows Operating system that is synchronized using the native Network Time Protocol (NTP) slave. This clock is provided by the NTP master embedded in the PCIe card.