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Vol. 54, No. 4, April 2005




Table of Contents




Environmental Influences on SMO Sensors’ Performance


Micromachined semiconductor metal oxide (SMO) gas sensors have good prospect of being solution as future gas sensor technology in terms of sensitivity, robustness, simple signal processing, low production cost and small size. However, there are some challenges for the  commercialization of SMO sensor to meet both performance-related and reliability-related requirements, especially false alarm problems caused by environmental induced drifts and shifts. Several environmental influence factors that affect SMO sensor’s performance, in terms of temperature variation, relative humidity and possibly others like light and oxygen partial pressure, are discussed in this paper. Principles behinds these influences are presented and schemes of eliminating these influences are reviewed and proposed.


Click <here> to download the full-pages article.


Jian-Wei GONG, Quan-Fang CHEN, Ming-Ren LIAN and Nen-Chin LIU





Accelerometers Measure Slow Moving Events


Two new accelerometers from Kistler Instrument extend the measuring range with slow moving measuring requirements from zero to 300 Hz. Kistler 8310A25 measures to 25 g and 8310A50 measures to 50 g. Both use a micro-machined capacitive sensing element that provides stability over the -40 oF to 185 oF temperature range. At 17 grams each, these newest members of the K-Beam accelerometer family measure tilt and other static or dynamic conditions.


Both accelerometers are hermetically sealed and ground isolated in a welded Titanium enclosure. In addition to adhesive mounting, four 4-40 or M3 mounting screws may be used. Both integral and unattached cable versions are available. A DC voltage supply of 6 to 16 Volts is required.


These accelerometers extend the measuring range of the series from 2 g and 10 g versions currently available. Typical applications are found in vehicular NVH studies, aerospace tests, large structure studies, human movement measurements and automation applications.



Don Beehler,

Kistler Instrument Corp.

75 John Glenn Drive, Amherst, NY 14228-2171

Tel.: 716-691-5100, fax: 716-691-5226

E-mail: don.beehler@kistler.com

Accelerometer 8310



Optical Dissolved Oxygen Sensor


Zebra-Tech Ltd introduced the D-Opto range of optical dissolved oxygen sensors. The D-Opto range includes the SDI-12 D-Opto, and the D-OptoLogger. Both instruments have been specifically designed for long term environmental monitoring of dissolved oxygen in streams, rivers and lakes.

Jobs that require long term dissolved oxygen measurements with minimal drift; the D-Opto sensor is for you.  D-Opto optical sensing technology is not only highly stable, but provides very accurate and reliable longterm DO measurements not possible with conventional DO sensing technologies. Additionally no oxygen is consumed during the measurement cycle removing the necessity for mechanical stirring in low or no flow. D-Opto has no consumable replacements and is un-affected by sunlight, reducing the operation costs.  Designed for harsh conditions, both instruments feature a biofouling control system to minimise the build up of bio-growth.

The SDI-12 D-Opto has a very low power requirement, making it suitable for remote sites. An SDI-12 instrument is simple to integrate with dataloggers. The instrument is supplied with a small interface module to ease installation into an established logging system. This interface also enables a computer to be directly connected to the D-Opto without disconnecting the instrument from the datalogger.

D-OptoLogger is a self contained DO logging instrument. It incorporates an optical DO sensor, logger and battery in a small, rugged underwater housing. The D-OptoLogger records percent saturation, oxygen concentration and temperature at user set logging intervals. Depending on the logging interval, the instrument can be deployed for up to several months. The instrument is supplied with windows based software for configuring the logger, download data, and calibration.


Murphy O'Neal

The Environmental Collective

Tel.: 0800 623 336, fax: 09 845 4339

E-mail: murphy@envco.org

D-Opto dissolved oxygen sensor



Laser Level & Positioning Transmitter, Measures Dry Bulk Solids

Over Extended Distances


Houston, TX - ASI Instruments, announced the LaserTrakЃ 80 laser transmitter for non-contact level measurement and positioning. Designed for a variety of bulk solids applications, the LaserTrak 80 measures position over very long ranges, at distances up to 500 feet (150 meters). The device also accurately measures level at distances up to 100 feet (30 meters). Whether handling plastics, grain, or aggregates, the LaserTrak 80 can measure any surface at any angle. The small wavelength of the laser means a narrower beam with virtually no beam divergence and, therefore, no false echoes. This provides high accuracy readings even when dealing with the most challenging circumstances, such as measuring into silo cones, inside silo chutes, and through narrow openings in protective grids.


The LaserTrak 80 features an all-digital design that provides speed and accuracy in a compact unit. An advanced timing system and self-correcting signal processing functions allow the device to accurately and reliably make measurements in the harshest conditions. The system can select the true signal even in the presence of dust, as is commonly found in silos of coal, plastics, or grain, as well as in underground mines or quarries.


Shari Worthington,

ASI Instruments,

PR Counsel,

Tel.: +1 508.755.5242

E-mail: sharilee@telesian.com

Level and Positioning Transmitter LaserTrak 80



Concentration Monitoring by an IR Detector Array


The infrared spectral region is ideal for concentration monitoring of various chemicals such as low water, CO and CO2. Ruggedness is of outmost importance in process applications. Most IR analyzer have a filter wheel to move from one wavelength to another or just scan, while the ChromaSpec IR from Applied Analytics, Inc. is based on an IR detector array with a linear variable filter (LVF) and has no moving parts. The ChromaSpec IR provides a cost effective maintenance free solution to the monitoring of gasses or liquids that absorb in the infrared spectral region.


IR light is absorbed by the sample the absotbance signals are then correlated to concentration. The detector is very compact , the LVF functions as the dispersive optical component and is glued directly onto the metal cap above the detector. The LVF array detector is extremely easy to operate, it has no adjustable parts, requires no cooling, is insensitive to vibrations or shocks and delivers one complete spectrum per second. The light source is collimated and optimized for maximum intensity. The resolution for most LVF’s is 1.5 % of the Entire wavelength range. The wavelengths covered by the LVF detector depends on applications and range from (for example) 1.4-2.4 µm, 2.6-2.8µm, 2.9–4.4 µm, 2.9-4.8 µm, 3.2–4.8 µm, and 5.5-11 µm.


Applied Analytics, Inc.

Tel.: (978) 461-0080

Fax: (978)246-7711

E-mail: sales@a-a-inc.com


ChromaSpec IR



DC Motor-speed Sensor


CDA Systems' CMSS56 DC motor speed module measures the speed of a commutated/ brushless DC electric motor based on the ripple in the motor's supply current. No physical contact or line of sight is required.


This device allows accurate testing of motor speed where the rotating parts of the motor are not accessible. These include automotive products such as electric fuel pumps and electric water pumps. However, the product was intended to address a wider range of applications where previously tested motors are embedded inside of another product, such as an automotive HVAC unit, a power-seat motor, or even a cordless power-tool.


CDA's modules re-calculate the motor speed on every single commutation of the motor under test, based on the time required for one complete rotation of the motor. This allows accurate speed tracking during acceleration, allowing accurate motor performance measurements to be made. The real-time response of the CMSS56 unit also makes it an ideal source of feedback for systems requiring motor speed control. Custom variations available on request.


Emmet Raftery,

CDA Systems Ltd.

481 Baker St., London, Ontario

Canada, N6C 1Y1

Tel.: (519) 438-2280

E-mail: eraftery@cdasys.com

CMSS56 DC motor speed module



H2S Analyser for High and Low Concentrations of Hydrogen Sulfide


The H2S-220 is a diode array UV fiber optics process spectrometer. It is designed to address on-line applications that require reliable, accurate, rugged and maintenance free monitoring of H2S concentration. Either a fiber optics insitu probe or flow cell can be used.


A bifurcated fiber optics cable is used to conduct light to and from the probe or flow cell. The insitu probe is inserted into a sintered metal filter to protect it.


While a variety of flow cells optical paths and materials of construction are offered two basic standard sampling system designs are offered; An extractive aspirated system with a  manual or automatic zero for gases and liquids, and a closed coupled extractive stack sampler with flow indication and automatic zero capability.


An industrial PC is used for data processing and user interface. The H2S-220’s user-friendly interface allows for modification of operational parameters including sampling system’s relays (no need for a PLC) , all the parameters can be modified through a touch screen interface.


Applied Analytics, Inc.

Tel.: (978) 461-0080

Fax: (978)246-7711

E-mail: sales@a-a-inc.com


H2S Analyser



Modbus-IDA and CAN in Automation Announce CiA DSP 309:

Interfacing CANopen with TCP/IP Part 2: Modbus/TCP Mapping


Modbus-IDA and CAN in Automation e.V. (CiA) have announced a licensing agreement, resulting in Specification CiA DSP 309-2: Interfacing CANopen with TCP/IP Part 2: Modbus/TCP Mapping. CiA DSP 309-2 provides a standardized mapping of CANopen data for transport on Modbus TCP networks. In the specification, Modbus Function Code 43/13 is reserved for this purpose. The reservation of this function code exclusively for CANopen is simultaneously being submitted to the Modbus-IDA RFC standardization process.


Monika Mack,

CAN in Automation (CiA)

Am Weichselgarten 26

DE-91058 Erlangen,

Tel.: +49-9131-69086-0, fax: +49-9131-69086-79

E-mail: headquarters@can-cia.org



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