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NI puts spotlight on instrumentation trends

Posted: 06 Jul 2005 ?? ?Print Version ?Bookmark and Share

Keywords:instrument control? gpib? vxi? pxi? controller?

In a recent seminar held at Alabang, Muntinlupa, Philippines, National Instruments (NI) discussed the trends in instrument controls and the future of instrumentation connectivity standards including GPIB, VXI and PXI.

NI tackled GPIB, which was first designed by Hewlett-Packard as an interface for HP controllers and instruments. NI utilized GPIB as an interface for industry standard PCs, side by side with their software offerings such as LabView and LabWindows. IEEE 488.1 defines the physical, electrical and mechanical GPIB standards, while IEEE 488.2 outlines the standard for controller software for interfaced instruments.

GPIB features robustness and reliability in terms of handshaking, securely shielded connectors as well as the capacity to handle errors. It is relatively fast compared to other buses at 1.5Mbps, and users and vendors favor it because it is easy to use and implement.

Hybrid systems featuring bridges such as the implementation of GPIB via Ethernet is employed for distributed instrument control, overcoming the limits of the GPIB specs. Under development is the HS488 standard which would boost the bus transfer rate of up to 8MBps, still utilizing standard GPIB cables.

GPIB communication involves a controller-in-charge in the form of a GPIB card, along with 'talkers' or 'listeners' in the form of the instruments, conversing via service requests and system messages. The communication exchange involves polling which allows the instruments to request service as well as increase the efficiency of the system.

NI offers NI Spy for its 488.2 software portfolio, which captures all types of communication between the GPIB and the instrument, and in the process point out items to be debugged.

Interchangeable virtual instruments

The company also presented the interchangeable virtual instruments (IVI) which showcases aiming to maximize the software reuse and integration from several vendors. IVI will reduce maintenance and support costs and downtime, and at the same time offer ease of use for the engineers with its simplified methods of validation and verification.

NI also tackled PCI eXtenstions for Instrumentation (PXI), combines the standard technologies of computer bus standard PCI bus, and VME eXtensions for Instrumentation (VXI), which can carry out physical size reduction of systems as well as more precise timing and interoperability on multiple manufacturers. PXI allows easy implementation and modularity on test and measurement systems, and the usage of software controls for synchronization purposes.

According to NI, GPIB still is the most popular among stand-alone control buses, but the Ethernet, USB and IEEE 1394 are starting to be considered as bridges in instrumentation control. Software is seen as the key to safeguard the users in any bus changes in the future. Mixed systems incorporating GPIB with other bus systems are seen as a noticeable aspect in the instrumentation industry trends.

"I would say that there would be a gradual change from GPIB-based to PC-based simply because of the increase in testing time," said YH Goh, field sales engineer for the Philippines at NI. "The computer-based measuring automation will give a high data throughput speed so there will be more test systems that would be computer-based," Goh added.

- Reden Mateo

Electronics Engineering Times- Asia

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