Windmill Software Ltd
Windows Engineering Software

February 2006

The Newsletter for PC-Based Data Acquisition and Control
Issue 91       February 2006
--------------------ISSN 1472-0221----------------------

Hello and thanks for subscribing to Monitor.  This 
month we launch a new feature: a round-up of the top
data aquisition and control news stories of the past few 
weeks.  How do I judge "top", well actually it's just 
the few that I liked the best - I hope you like them too.

Should you wish to cancel your subscription to Monitor 
you can do so at

* Windmill Notes: Monitoring Gas Sensors with a Strain 
  Gauge Measurement Package
* DAQ News Roundup
* Data Acquisition and Control Exhibitions

Windmill Notes: Monitoring Gas Sensors with a Strain 
Gauge Measurement Package

Gas sensors are typically made as heated wire elements 
which change in resistance as the target gas 
concentration changes. They can detect specific gases 
such as carbon dioxide or a group such as inflammable 

Because they are monitored using a bridge circuit to 
detect changes in resistance, the Windmill 751 strain 
gauge package is well suited for logging from one or 
more gas sensors.  This plugs into the PC's USB port.  
Having a sensing element and a reference element, they 
form half of a wheatstone bridge circuit.  The other 
half is formed by the boxed bridge-inputs unit (the 
594) which is included in the package.  This has 
several configuration options and you need to choose 
the half bridge input.

Power requirements for gas sensors are different to 
those for strain gauges.  Typically they require 
3 V DC at up to 0.5 A in order to heat and maintain 
the element at temperature. This means that an 
external supply will be required, since the USB is 
not able to supply that level of power. For a 
couple of gas sensors we used a voltage selectable 
plug-top supply capable of 1.25 A at 3 V.

The polarity of the gas sensor connection is 
important, so make sure the positive output of 
the sensor goes to the +IN input on the 594, 
and the negative output of the sensor goes to 
the -IN input on the 594, otherwise there will 
be no response to a change in gas concentration. 
The power is supplied to the sensor through the 
+EX and -EX connections of the 594, and the 
external power supply is connected through the 
+POWER INPUT and -POWER INPUT connections.  
The -EX may also be connecetd to the 0 V 
connection so that the negative supply of the 
bridge circuit is connected to the 594 Common.

The bridge circuit is suitable for monitoring 
changes in gas concentration, but a reference 
level is required. Typically this will be the 
open to atmosphere concentration.  Windmill 
software is used to setup the measurement 
channels for half-bridge strain gauge monitoring. 
In the Windmill ConfIML program you will need to 
specify the use of a 594 connection unit, and in 
Windmill SetupIML, the channels in use for gas 
sensors are specified as half-bridge configuration.  
At the channel level in SetupIML the zero level can 
be set to balance the bridge at atmospheric 
concentrations.  It is more convenient however to 
use the SGzero program (available free with the 
751 strain gauge package) since you can use this 
to rebalance the bridge at any time.

Further Reading
Windmill 751-SG - Strain Monitoring and Control

Computerised Strain Measurements

DAQ News Roundup

Welcome to our roundup of the latest findings in 
data acquisition and control.  

If you would like to receive news updates as they 
happen then grab our RSS newsfeed at  Read for information how.

Robot Moved by a Slime Mould's Fears

   A bright yellow slime mould that has been put in 
   charge of a scrabbling, six-legged robot.  The 
   Physarum polycephalum slime, which naturally shies 
   away from light, controls the robot's movement so 
   that it too keeps out of light and seeks out dark 
   places in which to hide itself. As the slime tried 
   to get away from light its movement was sensed 
   by circuit and used to control one of the robot's 
   six legs.  The robot then scrabbled away from bright 
   lights as a mechanical embodiment of the mould.  
   Eventually, this type of control could be 
   incorporated into the bot itself rather than used 
   Source: news service

Electronic Nose could Spell the end of Landfill Pongs

   Scientists at the University of Manchester have 
   invented a new device which remotely monitors bad 
   odours and methane gases at waste landfill and water 
   treatment sites. The device, which works like an 
   electronic nose, could be the solution many communities 
   and waste management companies, are searching for.  
   Currently there is no other instrumentation sensitive 
   enough to monitor low concentrations of odours and 
   gases on these sites.  Gases and odours are analysed 
   manually using handheld detectors and by panels of 
   volunteers asked to smell samples of air.
   Source: The University of Manchester

Call for International Standards to Shape the "Digital Home"

   Household connectivity is growing rapidly with more 
   and more electronic devices and networks within the 
   home distributing and using digital information. 
   Given the various technologies involved, international 
   standards that enable interoperability and security are 
   seen as key to bringing value and versatility to consumers, 
   making possible the use of diverse products, services and 
   sources, and therefore accelerating market development. 
   Source: The International Electrotechnical Commission (IEC)

New Design for Transistors Powered by Single Electrons

   Scientists have demonstrated the first reproducible, 
   controllable silicon transistors that are turned on 
   and off by the motion of individual electrons.  The 
   transistors are based on the principle that as device 
   sizes shrink to the nanometer range, the amount of 
   energy required to move a single electron increases 
   significantly.  This makes it possible to control 
   individual electron motion and current flow by 
   manipulating the voltage applied to barriers, or 
   gates, in the electrical circuit.
   Source: National Institute of Standards and Technology

Data Acquisition Exhibitions and Conferences

Continuing the quarterly list of exhibitions around 
the world in the data acquisition and control field

   Istanbul Turkey
   16-19 March
   Industrial automation fair.

National Industrial Automation Show and Conference
   Chicago Illinois USA
   20-23 March
   The event for automation and control engineers, 
   manufacturing managers and system integrators from 
   across the USA.

   Warsaw Poland
   21-24 March
   International fair for measurement and control.

IEEE Instrumentation and Measurement Technology Conference
   Sorrento Italy
   24-27 April
   Tutorials in instrumentation and measurement.

Hannova Messe: Interkama
   Hannover Germany
   24-28 April
   Trade fair for process automation.  From overall 
   system planning and control systems to field devices 
   and components, plus all the services needed for the 
   operation of industrial plants.

Sensor+Test 2006
   Nuremberg Germany
   30 May - 1 June
   International Trade Fair for sensorics, measuring 
   and testing technologies.
Sensors Expo & Conference
   Rosemont Illinois USA
   5-7 June
   Exclusively focuses on sensors and sensor-integrated 

   Lulea, SWEDEN
   12-15 June
   International congress and exhibition on condition 
   monitoring and diagnostic engineering management

* Copyright Windmill Software Ltd
* Reprinting permitted with this notice included
* For more articles see

We are happy for you to copy and distribute this 
newsletter, and use extracts from it on your own web site 
or publication, providing the above notice is 
included and a link back to our website is in place.

An archive of previous issues is at
and an index of articles at

Windmill Software Ltd, PO Box 58, North District Office,
Manchester, M8 8QR, UK
Telephone: +44 (0)161 833 2782
Facsimile: +44 (0)161 833 2190
E-mail: [email protected]


To receive Monitor every month please fill in your e-mail address below. We will not pass your address to any third parties, nor send you any unsolicited e-mail.


Previous Issue Next Issue