[TechView: Test]
Instruments Offer Fully Synchronized Data Acquisition Over Ethernet
Louis E. Frenzel
ED Online ID #18761
April 18, 2008
Copyright © 2006 Penton Media, Inc., All rights reserved.
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A key problem in data acquisition is acquiring data from many points spaced over a wide area. In industrial settings like large factories and mills, tall buildings, oil rigs, and large ships, sensors are widely spaced, making it difficult to correlate samples over time. Some method is needed to synchronize many channels to take the guesswork out of data interpretation.
The IEEE 1588 standard was developed to provide periodic synchronization in LXI standard data-acquisition systems, but it doesn’t provide the continuous synchronization needed in some applications. Dataq Instruments has solved this problem with its patent-pending synchronous Ethernet interface, which is now available in the DI-785 and DI-788 data-acquisition products (see the figure).
The DI-785 and DI-788 are 32-channel data-acquisition systems with a 14-bit resolution and a maximum sampling rate of 180.000 samples/s (150,000 samples/s daisy-chained). Both offer the synchronized distributed Ethernet interface and a built-in ac power supply.
The primary difference between the two units is that the DI-785 uses DI-5B input modules while the DI-788 uses DI-8B input modules. Both plug into a common backplane and provide selectable gains of 1, 2 , 4, and 8, isolation and filtering for RTDs, thermocouples, strain gages, and other sensors.
Unlike the competition, these systems embed the Ethernet switch in the unit, making an external Ethernet switch or hub unnecessary. A large system can be constructed using up to 100 m of CAT5 cabling between units that can be daisy-chained. Data is acquired across multiple units synchronously with zero latency between them.
Available now, the DI-785 and DI-788 cost $3995 each.
Dataq Instruments Inc.
www.dataq.com
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