Customer Solutions

Using LabVIEW to Access and Control a Harsh Environment Laboratory through the Internet

Author(s):

William Holmes, Lockheed Martin Energy Research Corp.

Industry:

Research

Product:

LabVIEW

The Challenge:

Developing an Internet-accessible data acquisition and control system (DACS) with real-time video conferencing capabilities for a harsh environment test bed at Oak Ridge National Laboratory (ORNL).

The Solution:

Using a server computer, LabVIEW software interfaces, and data acquisition hardware to comprise the local experiment control and data collection.

Oak Ridge National Laboratory (ORNL), while possessing core capabilities related to process and emissions monitoring, needed a readily accessible, cost-effective, and environmentally benign medium for test and demonstration purposes. We constructed the Harsh Environment Laboratory (HEL), which simulates industrial stacks or steam vents with high-humidity and elevated-temperature gas streams, to address continuous emissions monitoring issues as they relate to the instrumentation of the future. The test bed demonstrates the virtual laboratory concept. Instrument manufacturers, researchers, and other users can remotely operate or interrogate the test bed.

System Configuration
The harsh environment test bed consists of a vapor generator flanged to a stack section. The vapor generator has six inlet ports, a quartz heater, a water nebulizer, auxiliary heating, and a waste drain and collector. Gas flow through the generator has remote on/off control and is metered through individual mass flow meters. The stack portion is outfitted with flanges that provide ports through which samples may be drawn, probes can be inserted, or the stack interior can be viewed. Stack effluent gas is collected and purified before being exhausted from the building.

A server computer, LabVIEW software interfaces, and data acquisition hardware comprise the data acquisition and control system (DACS) for the local experiment. Client applications communicate through the Internet for remote control of experiment parameters and interrogation of real-time data, such as stack temperatures, relative humidity, pH, flow rates, gas concentration, and prototype sensor outputs. Data is viewed and stored at both the server and client locations. Video teleconferencing affords the remote user a sense of being at the test bed.

The Server (Local DACS)
The HEL DACS is a 100 MHz Pentium PC running Windows 95. We interfaced it to a Phoenix Contact InterBus-R command and control module (CCM) with a National Instruments AT-485/2 serial interface board for RS-485. Analog signals from sensors and monitors are interfaced to the CCM through analog and thermocouple input modules. Digital input and output modules control gas and vapor selection and status indication.

We use three video cameras at the HEL. A Canon VCC1 color video camera views the test bed area. Remote control of the pan-tilt-zoom functions are interfaced to the server through the onboard CCM RS-232 serial interface. We use the second and third cameras (both the Color CCD Telecamera, Howard Enterprises, Inc.) for viewing the interior of the test chamber and for video conferencing. The output of any of the cameras can be locally or remotely selected. Full duplex video transfer over the Internet is accomplished using CU-SeeMe software from White Pine, Inc. or a public offering by Cornell University.

The LabVIEW server application performs the following local functions -- control of test flow parameters; data collection, conversion, display, and storage; transfer of data via the Internet to client application (described below in The Client,); and video output selection. This server application receives remote commands via the Internet from the client application to perform these tasks -- verifying client authenticity, transferring encrypted real-time test data on request, executing test flow parameter changes, transferring feedback indicators, selecting video output, controlling camera pan/tilt/zoom functions, and providing real-time verification of safe test conditions.

The Client (Remote DACS)
When the client application links to the server application through the Internet, it transfers an authentication code. Upon validation, the server transfers encrypted data, camera selection, triaxial camera positions, and valve control status. The client decrypts the data and displays it in graphical and digital formats, including status indicators for camera selection, tri-axis camera position, and valve control. A validated user can store data, selecting which data is displayed in any of six graphical and digital displays, and request control of the remote system. If control is granted, the remote user can change test flow parameters, video display selection, and triaxial camera position. The selected video image is displayed using CU-SeeMe software.

The Challenge of Connectivity
A successful HEL data acquisition system depended on two types of connectivity. Because of the harsh environment being monitored, it was necessary to isolate the signal conditioning and data acquisition hardware from the server computer. This challenge was met by using the Phoenix Contact front-end equipment with its RS-485 communication link to the PC via the National Instruments AT-485/2 board. Using the serial port LabVIEW virtual instruments (VIs), we were easily able to develop reliable command handlers between the server program and the data acquisition equipment.

Connectivity over the Internet was necessary to make the data acquired available to client computers at remote sites. Once again, the LabVIEW-supplied VIs for TCP/IP were easily expanded to provide necessary services for both the server and client software. Several clients can make socket connections to the server to monitor HEL data. Only one client at a time can control the server output capabilities to change experimental conditions and/or to control the video returned by the CU-SeeMe connection.
Using the Internet for data reporting, experiment control, and video conferencing is an economical solution to the problem of remote user access to the HEL. Even clients without direct Internet attachments can use dial-in Internet connections to access this important experimental facility.

Conclusions
On-line sampling and analysis in a harsh environment, exemplified by incinerator stacks or exhaust vents with potentially corrosive high temperatures, steam, and/or aerosols, can be very challenging. The environment presents a variety of problems, from simple water vapor condensation in sampling lines, to sensor failure or instrument performance degradation, to a lack of fundamental understanding regarding the physical state in which the substances of interest behave. Development of a test bed that simulates many types of process vent and stack environments is a cost-effective approach. This facility can be used to demonstrate stack models and serve as an experimental platform on which to address more fundamental issues, such as materials stability and particle-phase/vapor-phase equilibrium in harsh environments.

Collaborative laboratories through telepresence technologies are part of vision of the Department of Energy (DOE) for its national laboratories. The HEL at ORNL exemplifies not only solving the challenges of remote operation and control, but also giving users a sense of presence at the facility. Scientists, engineers, instrument developers, manufacturers, or end-users can remotely operate and control performance monitoring experiments, transfer and view data, and perform teleconferencing simultaneously, all in real time. DOE's intention for these capabilities is to reduce costs , accelerate the acquisition of scientific knowledge, and improve final products.

For more information, contact:

William Holmes, Jr.

Oak Ridge National Laboratory

P.O. Box 2008

Oak Ridge, TN 37831-6006

Tel: (423) 576-8380

Fax: (423) 576-7830

E-mail: holmeswjr@ornl.gov

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