Honeywell Implements Distributed, High-Channel-Count Data Acquisition System

Author(s):
Sorin Grama - Cal-Bay Systems, Inc.

Industry:
Aerospace/Avionics

Products:
PXI/CompactPCI,

The Challenge:
Developing a distributed, large-channel-count data acquisition system with real-time and historical data analysis capabilities from multiple remote display clients.

The Solution:
Using National Instruments LabVIEW 7.0 to implement a distributed architecture that takes advantage of built-in networking protocols, saving weeks of custom software development time.

 

Requiring Dedicated Testing Facilities

Testing aircraft components such as turbines and generators requires dedicated test facilities that can subject the unit under test (UUT) to extreme pressures, temperatures, and other conditions similar to those encountered in real-life operating mode. Researchers initiate and monitor qualification tests from a control room, featuring multiple computer stations dedicated to specific tasks such as pressure and flow control, safety monitoring and simulation. During a test run, teams of engineers, technicians, and analysts work together to collect and analyze real-time and historical data from various subsystems. The atmosphere is similar to that of a space flight control room – everyone focuses on the UUT, but with a different perspective. A data acquisition system that acquires, displays, and records the critical test data is at the heart of this activity.

Designing a System to Present Data in Real Time

Honeywell Engines, Systems & Services in Torrance, California, challenged Cal-Bay Systems, Inc., with the task of implementing such a system. We were required to design a system that could collect more than 2,000 channels at sampling rates varying from 1 Hz to 100 Hz. In addition, the system had to make test data instantly available to six client PCs for display and on-the-fly analysis and collect every data point and store it to a central location where it could be available immediately for historical analysis using specialized software tools. Finally, the system needed to seamlessly switch back and forth between on-the-fly and historical data analysis.

Honeywell required a networked, distributed data acquisition hardware architecture to reduce the wiring throughout the test facility. The system had to interface to multiple Ethernet-based data acquisition devices. Besides collecting and logging data, the system needed to make the data available to a separate facility control computer, which would run the control loops for various pressure, flow, and temperature subsystems. Because of the real-time control requirement, the system had to publish the data to the control computer at a deterministic rate of 100 Hz using a real-time, dedicated network.  Finally, this application required data integrity maintenance. The system could never duplicate a test run; therefore, it had to acquire all the channels and store them for post-acquisition analysis.

Previously, engineers built data acquisition systems using various PC platforms, all of which had a concentrated architecture. The systems could acquire and display a very limited number of parameters. Engineers connected all instrumentation to a single PC, resulting in long wiring runs, which increased susceptibility to electromagnetic interference and physical damage. These systems were also limited to one data viewing station, which prevented multiple users from analyzing the incoming data in real time.

NI PXI, SCXI, and LabVIEW Real-Time Provide Results

We based our hardware design on the PXI platform for its ruggedness and multiple analog and digital I/O hardware offerings. We used the SCXI hardware to expand the channel number and provide signal conditioning to sensors such as thermocouples and flow meters. We selected a PXI controller running LabVIEW Real-Time as the main data acquisition engine. This controller communicates with a host PC through a real-time reflective memory interface. The host PC stores the data to a RAID disk array and, at the same time, makes it available to the client PCs for display.

We based our software on the LabVIEW platform for its ease of use and tight integration with the hardware. In addition, using LabVIEW Real-Time, we ran the control and acquisition program on the PXI controller as an embedded process without operating system overhead. With this system, we can deterministically acquire more than 2,000 channels of data and make them available to the control computer via the reflective memory ring. Normally, we would spend a year designing a system, such as this. However, using NI products, we completed our project in seven months, reducing development time by more than 40 percent.

Based on this experience, we have developed a high-channel-count data acquisition product that uses LabVIEW Real-Time to collect and publish data over an Ethernet link.  The unit operates like a stand-alone instrument and can be accessed from a host PC using a simple LabVIEW instrument driver. 

For more information, contact:

Sorin Grama

Cal-Bay Systems, Inc.

16 Technology Drive, Suite 160

Irvine, CA 92618

Tel: (949) 727-2010

Fax: (949) 727-2022

Email:   info@calbay.com

Web:    www.calbay.com

 

 

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