Industrial Data Acquisition Platforms

Industrial data acquisition and control (IDAC) systems are powerful, headless, distributed systems designed to increase efficiency through monitoring and control. Through high-speed monitoring and analytics, IDACs can provide insight into the health of an asset in order to predict failure and reduce downtime. These systems can interface with every aspect of the Asset Integration Architecture (AIA) to form a vast network of interconnected systems that distill information for fast and reliable decision-making. From smart grids to smart machines, IDACs acquire, analyze, and communicate information on both an asset and enterprise level. Through on-board heterogeneous processing, IDACs can make hard real-time decisions in microseconds, saving time, network bandwidth, and central processing power. In addition to monitoring, IDACs have the input/output and processing capabilities needed to perform advanced, high-speed control, based on information obtained through monitoring. These capabilities also enable IDACs to acquire, analyze, and communicate processed information to the control system without slowing down the control loop. In turn, this information can be used in real time to improve asset health, efficiency, and throughput by optimizing control algorithms and maintenance schedules.

Basic Elements

IDACs are defined by a few key hardware and software elements that are tied together through a unified integrated development environment. Because many assets are often located in remote, rugged, or even dangerous environments, this hardware and software solution has to be durable, reliable, and capable of stand-alone operation in order to ensure continuous control and monitoring, even in the worst conditions, including loss of network communication. The primary elements of an IDAC are:

• Heterogeneous processing: In order to get the best response time and throughput, IDAC systems combine a host of processing options to optimize performance for various tasks. These processing elements include multi-core processors, digital signal processors, field-programmable gate arrays (FPGAs), and lookup tables. Each of these elements stores and processes information using different methods, which makes them suitable for different tasks. Low-level tasks such as high-speed parallel processing can be moved to the FPGA, which is optimized for such tasks. High-level tasks like communication and software architecture can be run on the processors. Each element is user-programmable so the hardware can be combined in many different ways to achieve the flexibility of a custom design with an off-the-shelf solution. To further simplify a custom design, many of these elements have been integrated into a single chip known as a system on a chip (SOC). Because they integrate many types of processing elements, IDACs also can be configured to act as vision, motion, or human machine interface (HMI) systems without changing any core components. For this reason, these IDAC systems are often described as “software defined,” in that it is the software that defines the hardware functionality.

• Software and operating system: The Internet of Things adds a lot of complexity to system design, so to remain efficient, simplifying in every way possible becomes paramount. Having an integrated software package that is hardware-aware is key to reducing such complexity. This software abstracts low-level, low-value tasks so the user can create a framework of reusable code that can be leveraged across many applications. When the software and hardware are tied together, the hardware can then be upgraded to the latest processing elements with maximum code reuse. Security is another challenge presented by the Internet of Things. When assets can be manipulated from almost anywhere in the world, the need for security grows. To address this, IDACs are based on an IT-friendly operating system that can be securely provisioned and configured to properly authenticate and authorize users, to maintain system integrity, and maximize system availability. They are also based on an open OS so developers around the world can unite and develop the latest in embedded security.

• Input/Output (I/O): In order to be effective, IDACs need to get information to and from the asset in the most accurate and efficient way possible, which is usually through a network of sensors and actuators. The I/O of an IDAC system offers the means to translate these real-world signals into the digital world for processing, through analog-to-digital and digital-to-analog converters. As important as processing is, the calculations are only as good as the I/O generating the data. For this reason, the I/O in an IDAC is capable of very precise and high-speed sample and update rates (>1 kS/s) for a high-fidelity insight into an asset’s performance. A common application in which such rates are required is condition monitoring of spinning machinery, where sample rates can reach hundreds of kilo-samples per second. The I/O has been modularized so that a single IDAC system can adapt to many different assets and changing sensor requirements. The I/O modules feature a wide range of signal conditioning in order to accommodate any sensor required by the asset. In many ways, the I/O acts as both an analog and digital means of communication between the asset and the processing.

• Communication: In addition to the communication between the asset and the processing layer, Ethernet-based communication protocols allow asset systems to communicate with other assets and with the enterprise. In the past, these protocols were proprietary to the individual manufacturers, which made it difficult to maintain a vast network of assets. IDACs solve this problem by supporting many communication protocols. There remains, however, a need for a standard universal communications protocol to allow further simplification and increased performance.

The following diagram maps the key features of an IDAC to our Asset Integration Architecture.

Applications

Many applications require I/O and processing. In the following, we discuss three types of application in which IDACs have been successful:

• Condition monitoring: Condition monitoring is the monitoring of assets in order to prevent and predict failure so as to prevent unscheduled outages, optimize asset performance, and reduce repair time. It is the quintessential application for an IDAC system. From power generation to industrial manufacturing, IDACs can be configured to acquire and process data to prevent and predict asset failure. See case study: Remote condition monitoring of London Underground track circuits

• Smart machines: Smart machines are high-performance machines with built-in intelligence that enable them to adapt to changing conditions and tasks. They come in many shapes and sizes and usually integrate many disparate features such as motion, vision, custom protocols, HMI, control, and monitoring. Because IDACs are so versatile in their processing and I/O, they can provide a single platform from which to build such a machine. See case study: Viewpoint systems improves gear finishing using a real-time control system

• Smart grid: The idea of creating an electrical grid that can react to changing grid conditions in order to reroute power, improve power quality, or self-heal is becoming a reality. The smart grid and its related standards are evolving to meet these changing conditions. IDAC systems are one of the key technologies behind the smart grid because they have the I/O, processing capability, and open architecture needed to adjust to the changing power standards and to perform power calculations. See case study: Increasing power service reliability and energy security with MicroGrids

Examples

One example of an IDAC system is the CompactRIO system from NI. Powered by LabVIEW reconfigurable I/O (RIO) architecture, CompactRIO combines a processor, user-programmable FPGA, and modular I/O with the LabVIEW integrated development environment. Because the system is so versatile, CompactRIO can communicate with open and proprietary protocols to integrate with existing systems or operate as a stand-alone solution. The CompactRIO hardware’s software-designed functionality runs on an open, real-time Linux OS that allows the system to be customized as a monitoring and/or control solution.

Other examples of IDAC systems can be found in both custom hardware and high-performance programmable automation controllers, or in a combination of the two types of system.

Differentiation

• Wireless sensor network technologies: Both IDACs and wireless sensor network (WSN) technologies can be used for monitoring, but they differ in terms of performance and channel count. WSN nodes acquire data from a few channels at regular intervals at a relatively slow rate (<1 kS/s), perform some minor processing, and then send that data back to a central processor for more in-depth processing. These systems are great for monitoring fairly static conditions that do not require quick decisions. On the other hand, IDACs can handle hundreds of channels at rates up to 1 MS/s, perform more in-depth processing, and report changes as they occur. IDACs, consequently, are designed to monitor more dynamic systems that require on-asset processing to make decisions quickly. The two types of technologies can operate together, with the IDAC acting as a central hub to collect and process data and the WSN nodes supplementing the main application.
• Programmable logic controllers: Both IDACs and programmable logic controllers (PLCs) can be used for control, but they differ in performance. PLCs run at relatively slow loop rates (<1 kHz) and are designed for simple control tasks. Users must tack on other systems to add more advanced functionality for things like vision, motion, or custom protocols. IDACs, on the other hand, can achieve higher loops (>100 kHz) and can handle more advanced control algorithms, vision, motion, and customer protocols. PLCs offer an industry standard and can be easier to program and use for simple tasks. However, for more complex functions involving high-performance control or integrating other tasks, IDACs are more useful. The two are often paired together to communicate with one another, with PLCs providing the main control loop and the IDAC tackling specialized tasks.

The following table shows the key differences between an IDAC, wireless sensor networks, and PLCs.

Recommendation

When considering an IDAC system, take both current and future needs into account. No one can predict the future, but it is important to be prepared for it. Black box solutions may solve today’s challenges but they do not have the flexibility to adapt to changing standards, sensors, or applications in the future. Choose an IDAC that is flexible with an open platform to adapt to these ever-changing variables. Otherwise, you will need to replace whole systems instead of performing simple firmware and component updates.

Outlook

One of the biggest challenges facing the Internet of Things in the industrial sector is the lack of an open, universal, Ethernet-based communication protocol that has the bandwidth and determinism to meet the needs of today’s high-performance machines and networks, and can grow with advancements in Ethernet technology to meet the needs of tomorrow. One promising technology that could eventually meet these needs is the time-sensitive network (TSN). The Institute of Electrical and Electronics Engineers (IEEE) has formed a TSN task group to evolve IEEE Standard 802.1 to meet these requirements. There is still much work to do to ensure that these standards meet the needs of your application – get involved with organizations like the IEEE and the Industrial Internet Consortium to make you voice heard.

We would like to thank James Smith and Brian Phillippi from National Instruments for the contribution of this chapter on Industrial Data Acquisition Platforms.