Flexibility, Integration Key For FPGAs in Automation

Field-programmable gate array (FPGA) chips have been around since 1984, but this venerable technology continues to find a dedicated user community in industrial automation.

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According to Mike Trimborn, group manager, LabView R&D, at National Instruments Corp. (NI, www.ni.com), an automation supplier based in Austin, Texas, “FPGA technology provides the reliability of dedicated hardware circuitry, true parallel execution, and lightning-fast closed-loop control performance.”

The operative phrase is “field-programmable.” Unlike application-specific integrated circuits, known as ASICs, which have instructions “burned in” that cannot be changed, FPGAs are reconfigurable after deployment. Unlike microprocessors that require an operating system to access all the power buried within, FPGAs require only a tool set for the programmer to download code.

As Trimborn explains, “An FPGA is a device that contains a matrix of reconfigurable gate array logic circuitry. When an FPGA is configured, the internal circuitry is connected in a way that creates a hardware implementation of the software application. FPGAs are truly parallel in nature, so different processing operations do not have to compete for the same resources. As a result, the performance of one part of the application is not affected when additional processing is added. Also, multiple control loops can run on a single FPGA device at different rates.”

This parallel nature and ability to perform multiple control loops form part of the benefits of the technology. “A single FPGA can replace thousands of discrete components by incorporating millions of logic gates in a single integrated circuit (IC) chip,” continues Trimborn. “The internal resources of an FPGA chip consist of a matrix of configurable logic blocks (CLBs) surrounded by a periphery of I/O blocks. Signals are routed within the FPGA matrix by programmable interconnect switches and wire routes.”

FPGAs offer high reliability in addition to high speed. Trimborn points to the example of a proportional-integral-derivative (PID) loop running in NI’s LabView FPGA module that executes in just 300 nanoseconds. PID control is a basic algorithm used in process control.

Safety on a chip

One new application for FPGAs in the industrial automation market is a machine safety release from Altera Corp. (www.altera.com), a programmable logic technology company based in San Jose, Calif. In this application, Altera has developed a safety data package approved by the German testing and certification firm TÜV. Says Frank Foerster, market development manager, industrial, at Altera, “The TÜV-validated industrial-safety data package shortens development time as much as two years. The programmability of FPGAs protects development investments and removes risk of functional obsolescence in safety critical designs, and the easy system integration of FPGAs also helps manufacturers lower total system cost by replacing functionality of DSPs (digital signal processors), microprocessors and other semiconductors.”

Today’s safety systems and new legislation require provision for more complex networked and distributed safety functions. Implementing a system such as this could require multiple processors. According to Foerster, “Total system cost can be lowered by an FPGA through consolidation of several components into the one chip including safety controller, fieldbus controller and application microcontroller.”

Jason Chiang, senior technical marketing manager, Industrial Business Unit, at Altera, looks at the practical aspect of customers who build the chips and technologies to enable today’s industrial networking. “In the fragmented industrial Ethernet landscape that includes EtherCat, Ethernet Powerlink, EtherNet/IP and Profinet, customers can implement the different networks on a single FPGA, then instantiate different protocols. This simplifies the implementation process.”

Despite closing in on its 26th birthday, FPGA technology continues to enable new applications for industrial automation.

Gary Mintchell, gmintchell@automationworld.com, is Editor in Chief of Automation World.

National Instruments Corp., NI
www.ni.com

Altera Corp.
www.altera.com

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