Integrated Linux Automation Controller

  • September 27, 2013
  • National Instruments Corporation
  • Feature

National Instruments Embraces Real-time Linux

By Bill Lydon, Editor

The most interesting announcement at National Instruments’ NIWeek 2013 was the CompactRIO model cRIO-9068.  The new high-performance controller has a dual core ARM processor and FPGA on the same chip that supports LabVIEW and Real-time Linux. Onboard interfaces include two Gigabit Ethernet ports, USB, and three serial ports. This looks like a great platform for industrial automation applications because it incorporates control, optimization, analytics, and business enterprise interfaces.

CompactRIO cRIO-9068 has 8 I/O Slots

Automation and control applications are programmed in LabVIEW. There are over 70 I/O modules available for CompactRIO including voltage, temperature, digital in/out, voltage/current outputs, relay, motion, strain and bridge, counter/pulse, and accelerometers. Communication modules include DNP3, serial, CAN, and PROFIBUS.

The National Instruments (NI) cRIO-9068 controller has a Xilinx Zynq SoC (System on Chip) that combines a 667 MHz dual-core ARM Cortex-A9 processor and an FPGA. The tight integration of the processor and FPGA on the same chip die enables application engineers to develop high performance applications that run simultaneously, executing on the FPGA while other tasks run on the dual-core ARM CPU under National Instruments Linux Real-Time operating system. By placing an FPGA between the processor and any application-specific I/O, NI boosts the flexibility and processing capability of the overall system. The combination of these three elements—processor, FPGA, and I/O—creates an architecture with reconfigurable I/O in which the FPGA can serve as a co-processing engine. The FPGA is transparently programmed using National Instruments LabVIEW graphical design software.

FPGA Basics

It is important to understand FPGA fundamentals to appreciate the power of this approach. FPGAs contain programmable logic components called "logic blocks" and reconfigurable interconnects that allow the blocks to be "wired together" with software. Logic blocks can be configured to perform complex combinational functions or merely simple logic gates like AND, OR, and XOR. The incorporation of analog functions, including differential comparators, analog signal conditioning, analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) in FPGAs, make them versatile for all automation applications. Because of the FPGA architecture, a major advantage is that functions run in parallel just like unique dedicated hardware, providing extremely high performance. Building applications in the environment unburdens application engineers from designing around resource and timing issues. In contrast, microprocessors in PLCs and automation controllers only provide the appearance of applications running in parallel using a real-time operating system to share the processor by using time slicing because the CPU can only execute one instruction at a time.

In the past, FPGA technology was only used by engineers with a deep understanding of hardware design. Originally the FPGA configuration and programming was done using a hardware description language (HDL) similar to that used for designing application-specific integrated circuits (ASIC). National Instruments simplified and demystified the use of FPGAs with LabVIEW to program them using their graphical block diagrams. NI RIO hardware, combined with LabVIEW system design software, allows those with application knowledge to leverage the power of FPGAs without needing the programming knowledge.

NI Linux Real-Time

National Instruments has developed their Linux-based real-time OS (RTOS) by working with the open-source community and contributions from partners. This RTOS is on the new NI cRIO-9068 controller and are fully supported in the NI LabVIEW 2013 development environment with the LabVIEW Real-Time Module. To learn more NI has a white paper, A Real-Time Preemption Overview.

Targets that run NI Linux Real-Time operating system can greatly benefit from the vast ecosystem of IP available for Linux. The incorporation of real-time RTLinux in the cRIO-9068 controller provides the opportunity to leverage open source software for a wide range of tasks including embedded databases, advanced analytics, and enterprise system interfaces. Linux has been growing in popularity for real-time embedded system design in large part for a number of reasons including that it is open source with a large and community of users contributing improvements and support. National Instruments has embraced this trend by contributing to the Linux community and supporting Linux Real-Time.

New Building Block

The CompactRIO cRIO-9068 could well be a strong building block for the newer more powerful system architectures that I have been writing about in recent articles including Automation & Control Trends in 2013, Simplifying Automation System Hierarchies, and Is it time for a new automation architecture?

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