Key points
SCADA has come a long way from the days of dial-up modems and RTUs (Remote Terminal Units) that were little more than data collection and relay boxes.
But at its core, the modern SCADA system still solves a key problem of asset owners with remote assets: maintaining visibility into, and supervisory control of, critical operations representing significant financial investment.
Moving beyond traditional data gathering, the SCADA system of today is becoming much more than that. Today’s SCADA system offers asset owners a platform for applications to control and optimise their operations, and enables them to improve reliability and safety of their processes by delivering critical diagnostic and health information.
This information enables proactive instead of reactive maintenance practices, reducing process downtime. In the near future, as the era of `Big Data’ dawns on the SCADA world, delivering true process intelligence from the vast amounts of new data types being gathered with value-added applications, will become even more critical.
The evolution of SCADA systems
SCADA systems are generally recognised to have progressed through three distinct phases of evolution with a fourth on the horizon.
Early in the evolution of SCADA systems, the primary paradigm in computing was that of the mainframe system, and SCADA systems of that era have been generally described as monolithic.
In these earlySCADA systems, the RTU was generally used only as the communications gathering point for the field, and served the sole purpose of relaying information back to the mainframe computer – generally over low-bandwidth serial radio networks or dial-up systems.
Due to the limited nature of computing and communications technologies available at the time, RTU protocols were relatively simple and for the most part little supervisory control was exercised.
These systems were usually limited to a single facility, and interoperability between hardware from one vendor and software from another, was virtually non-existent.
Later, as processing power and networking technologies improved, the computing paradigm shifted to a distributed architecture with PCs becoming ubiquitous, and SCADA systems followed suit. SCADA system architectures became more layered and distributed.
On larger systems with many hundreds of RTUs, the RTUs would feed data into field servers, sometimes called front end processors (FEPs), which would in turn be networked to the main host system.
In this stage of evolution, RTUs and host systems started to extend functionality beyond basic data capture and reporting, and began to take on some simple control and alarming features.
SCADA systems became capable of monitoring larger operations over multiple sites, as the distributed nature of the architecture and the quickly declining cost of computing power enabled a more modular and easily scalable approach to SCADA systems.
In the third stage of evolution, the current `Networked’ era, the modernisation of SCADA systems continued to be driven by the advancement of computing and networking technologies. The SCADA system architectures implemented in the Networked era continued to use the distributed model.
SCADA software vendors
SCADA vendors providing only the host software and project implementation services began to enter the market. Driven by users, SCADA software vendors began to place much more focus on moving away from the monolithic model of closed proprietary systems, to being able to gather data from a variety of RTUs, PLCs, and other end devices.
It became possible for asset owners to mix and match controllers and hosts and to choose the best products for their specific needs.
The trend towards openness and connectivity of disparate vendor devices and systems has continued in recent years through SCADA vendor support of the various incarnations of the originally named OLE for Process Control (now referred to as Open Platform Communications or OPC protocol).
Perhaps the biggest advancement in this era in SCADA systems has been the adoption of Internet Protocol as the primary means of communication. IP networks have enabled SCADA systems to deliver much more intelligence about the process being monitored and controlled.
RTU and PLC vendors embraced IP, and IP versions of both industry standard protocols such as MODBUS and vendor proprietary protocols were developed.
In comparison to traditional serial networks, where generally only one RTU may be communicating to the host at one time, IP networks enable the host to gather data from multiple RTUs simultaneously, and more importantly, make it much easier and quicker to gather data on demand as needed.
In combination with higher-bandwidth wireless wide area networks over IP radios, cellular and satellite, as well as high speed fibre communications backbones, SCADA systems are now capable of providing an order of magnitude more data, more operational intelligence, and more control of critical field processes than their previous incarnations.
Today SCADA systems are not “only but also…..”
During this modern era of SCADA systems, both RTU and SCADA software vendors have greatly expanded the capability of SCADA systems to not only monitor, but also to control and optimise critical operations through applications running on the SCADA platform, either within the RTU or on the host system.
RTU vendors have adopted much of the functionality traditionally offered by PLCs, such as programming tools for IEC61131, but more importantly are also providing pre-developed, standardised configurable applications to optimise common processes.
For example, Emerson’s SmartProcess Oil and Gas applications suite offers several pre-configured RTU applications tailored to oil and gas production operations, for artificial lift monitoring and optimisation, surface control, and tank monitoring.
RTU optimisation applications offer significant value to the end user because optimisation tools can be standardised across their dispersed operations for consistent results – avoiding reliance on regional integrators to develop point solutions that may deliver different, unpredictable results, and that may be based on different standards for support and ongoing development.
SCADA system embedded applications
Some SCADA software providers also feature tightly integrated or embedded applications that provide a variety of value added features to optimise operations at the full field or full pipeline level, or to monitor and proactively manage asset health.
In pipeline implementations, the use of applications such as line pack for gas pipelines (to calculate the volume of gas stored in the pipeline system), or batch tracking for oil pipelines (to track the progress of liquids batches through the pipeline system), are common and expected by asset owners.
Asset management and health monitoring capability is also becoming more tightly integrated with some SCADA platforms. Emerson, for example, has tightly integrated its asset management and health monitoring software (AMS Suite) with its SCADA software platform (OpenEnterpriseTM).
This integration allows HART device diagnostic health data from the field to be tracked and reported by AMS Suite software, enabling more proactive device maintenance practices that ultimately lead to more efficient and more reliable operations.
And there is more to come….
The future of SCADA shows promising possibilities. As has been the trend in the past, future improvements are likely to be closely tied to the continuing developments in information technology and networking.
Cybersecurity, for example, has already become a key consideration in the design of SCADA systems and will continue to be a concern, especially as SCADA vendors are moving to web-based platforms and providing access to the SCADA system through mobile devices.
In addition, most seem to agree that the process automation market and the information technology world in general is entering a new era commonly characterised by `Big Data’ enabled by ‘the internet of things’.
With a vast increase in intelligent sensors monitoring both more assets than were previously monitored and monitoring more data points on existing assets, SCADA systems will be required to deliver orders of magnitude more data to the user.
Connectivity and availability will continue to be important to SCADA users, but continued adoption of real-time condition monitoring and optimisation tools will be critical to deliver true process intelligence.
