Managing Tomorrow’s IIoT Data Volumes with Remote Telemetry Units
May 21, 2021
Remote telemetry units (RTUs), or “edge computers” of critical networks, are needed to handle larger data volumes and minimize security breaches in the Industrial Internet of Things (IIoT).
Predictive analytics is a fundamental value proposition for the IIoT, where responding faster to issues, or taking action before issues occur, is key to a high return on investment. Data required by these algorithms depends on communications networks to carry this vital information. For a robust design, you must assume these networks will become congested, potentially fail, or face increasing risks of cyberattacks. Here, Craig Abbott, sales manager for the Asia region at Ovarro, explains why remote telemetry units (RTUs) are vital for managing these design parameters.
The concept of the Internet of Things (IoT) is based on gathering data from multitudes of low cost sensors across high-speed communications links. The industrial version of this, the IIoT, uses the data to glean additional information for optimizing the process plants, railway links, cities, and utilities that we rely on every day.
It’s vital that the link between the sensors in the field and analytical processes, often in the cloud, are as secure as they are powerful. The notion of failures in these critical networks is increasingly unacceptable.
That’s why RTUs have, for decades, been used to manage communications links and distribute processing power. These telemetry units are capable of analyzing more data than can be easily transmitted.
Carry On Monitoring
RTUs collect data from sensors at the remote location and process it locally for a local, low-latency response. The link between the sensor and the RTU is typically a short length of wire, which is reliable and secure. The sensed data allows RTUs to manage pumps, valves, compressors, and switchgear independently of any communications link.
Real-time, process oriented calculations are all performed locally. Any process control, analytics, or asset management algorithm can also be done locally. Even if there’s a catastrophic communications malfunction, control and monitoring can carry on regardless and provide continued, uninterrupted operations and analysis.
Some data is still required centrally to manage the entire network, and gaps caused by communications failures can reduce the effectiveness of any holistic analytics. Security of data is therefore a key feature of RTUs. They are not only process controllers, but also data loggers that maintain a local historian, a database of sample values and events, until communications are restored. In fact, the latest RTUs can store hundreds of thousands, and potentially millions, of events. To give this some perspective, 100,000 events is about 140 days’ worth of hourly samples from 30 remote sensors.
RTUs also support multiple communications channels. If a primary communications channel fails, a secondary or even tertiary channel can be utilized. One of the most demanding applications faced by Ovarro and its customers is managing safety critical systems on a railway line. There are RTUs that switch between up-to seven channels to make sure data always gets through. These channels can include hard-wired cables, global systems for mobile (GSM), radio, and satellite communications options.
In addition, RTUs are autonomous and can maintain local control and data security for extended periods without supervisory oversight. This means they can also provide an extra trusted layer in fully-automated, unmanned, or lights-out production scenarios. All of which brings us to issues of cybersecurity.
Safe and Secure
Many industrial applications are linked intrinsically to public safety — instances include the supply of fresh water and removal of wastewater, transporting people, and the transport of potentially hazardous materials like oil and gas.
This especially applies to critical network infrastructure where any interruptions to these services could cause serious disruptions to people’s lives, or the economy. That’s why the UK’s National Cyber Security Centre (NCSC) works with suppliers, like Ovarro, to review equipment standards and ensure the security of equipment used on public services.
Cybersecurity challenges should be met transparently. For this reason, Ovarro now regularly shares its up-to-date common vulnerabilities and exposures (CVE) reports online. Our CVEs outline any cybersecurity vulnerabilities that have been discovered along with available updates, solutions, and methods to mitigate risk. Ovarro’s own commitment to cybersecurity includes our adherence to the ISO 27001 standard, the leading international standard for information security management. Companies often demand this before they work with us.
Ovarro RTUs already take advantage of highly secure passwords and encrypted communications. However, cybersecurity is an ongoing pursuit. We are currently working towards the IEC 62443 standard, which will become ever-more critical as businesses and industrial environments grow increasingly automated.
Data Concentration and Compression
Communication networks are also seeing rising volumes of data, with increasing loads on both the main server and the communications networks that connect to it. Every new analytical algorithm, or asset management tool, requires access to increasing quantities of data. No matter how fast communications links become, there will always be a demand for more data from more sensors, along with more security checks, and higher levels of encryption. This creates the potential for communications overload.
One method to streamline data acquisition is to use RTUs as data concentrators. If there are multiple devices at a single location, it can be tempting to collect data from each and every single device independently. An RTU at site can simplify the communications network by aggregating all the data for all the devices, thereby concentrating the information into a single source. This is especially important for critical sites with multiple backup communications channels, as the RTU also has the role of being the communications channel manager.
Furthermore, an RTU can minimize congestion by condensing the data to only what’s necessary. For control purposes, an RTU may sample the level of a water tank, or the voltage on a train power line, several times per second, but limit communications traffic by sending only key details to a central main server.
OVA066 – Managing tomorrow’s large IIoT data volumes – 1: An RTU can sample the voltage on a train power line, several times per second for alarm and control purposes, and only send key details to the main server.
For example, an asset management algorithm may make use of the minimum, maximum, average, total, and standard deviation for a data point as it changes during an hour. Calculating these parameters in the RTU and sending only the five calculated values, rather than all 3,600 one-second samples, reduces communications traffic by 99.9%. With this simple compression method, RTUs can provide an insight into remote systems with next-to-no impact on available bandwidth.
Most RTUs are only used to manage input and output (I/O) points from local sensors, analyze them, and respond to change. These are today’s algorithms — and there is already an abundance of spare capacity available to handle the algorithms of tomorrow, as IIoT and newer predictive functions are deployed. For example, the Kingfisher CP-35 runs a Linux operating system on a 1 GHz processor. A fleet of 100 of such RTUs across a network gives 100 GHz of processing power in the field.
OVA066 - Managing tomorrow’s large IIoT data volumes – 2: The Kingfisher Plus RTU can be fitted with dual power supplies, dual CPUs, and multiple, redundant communications modules.
No wonder, then, that RTUs are frequently referred to as being “field mountable edge computers”. In the IoT, the role of an edge computer is to pre-process data and act before the data is passed on to the main server. This allows a faster, low latency response and minimal traffic between the central server and the edge.
This is exactly the role that an RTU fulfils in the IIoT, now and into tomorrow. The design basis for SCADA may be that communications can, and likely will, fail, but RTUs have always been ready to maximize data access, maximize data security, and minimize data congestion, irrespective of communications stability.