Windmill Software Ltd
Windows Engineering Software

January 2006

The Newsletter for PC-Based Data Acquisition and Control
Issue 90        January 2006
--------------------ISSN 1472-0221----------------------

Welcome to our first issue of 2006.  This month we 
discuss how researchers into climate change have been 
using Windmill to monitor and control environmental 
conditions.  We also give an index of articles 
published in previous newsletters.

You've told us you are interested in reading about
real-world applications of data acquisition systems.  
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are using Windmill please get in touch and tell us about 
your system.  Either e-mail [email protected] or 
fill in the form at

If you have tried using Windmill but have had problems, 
e-mail us and we'll try and sort them out for you.

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cancel your subscription you can do so at

* Windmill News: Windmill Aids Climate Change Research
* Excel Corner: Combining Stacked and Clustered 
  Column Charts
* Index to Previous Articles

Windmill News: Windmill Aids Climate Change Research

Atmospheric carbon dioxide concentration and temperature 
are increasing.  Periods of low water availability are 
expected to increase in Mediterranean and other 
ecosystems.  Researchers in Spain at the Institute for 
Natural Resources and Agricultural Biology of Salamnca 
(CSIC) and the University of Navarre, have simulated 
predicted increases in CO2 and temperature and 
investigated the effects on crops.  To monitor and 
control environmental conditions they used Windmill 
software and a Microlink 751 data acquisition unit 
which they connected to their PC's USB port.

Much of previous research on elevated CO2 has been 
done in fully-controlled environments using constant 
temperature and electric lighting.  Plant behaviour 
in the field frequently differs from that in such 
facilities.  The Spanish researchers used temperature 
gradient tunnels to more realistically simulate 
aspects of the effects of future enviromental change.  
Their near-field technique had the added benefit of 
being enormously cheaper than other similar experiments.

CO2 Concentration, Temperature, Humidity and PAR Measurement

The temperature gradient tunnels contained measuring 
and control equipment.  Carbon dioxide concentration, 
for example, was continuously monitored by an 
infrared gas analyser.  Ventilated temperature and 
humidity sensors and air probes connected to another 
infrared gas analyser were placed 60 cm above the 
plants.  Quantum sensors were placed on top and 
inside each tunnel to record photosynthetically 
active radiation (PAR).  The data was continuously 
recorded by a computer using the Microlink 751 DAQ 
unit and the Windmill software.

CO2 Cylinders Opened and Closed under Windmill Control

As well as the standard Windmill software suite, 
which includes logging and charting modules, the 
researchers used the Windmill Test-Seq programming 
tool.  With this they controlled solenoid valves 
which kept open or closed one of two sets of CO2 
cylinders supplying the gas to the elevated CO2 
tunnel. When CO2 concentration decreased below a 
fixed level, signalling that one of the cylinder 
sets was exhausted, the corresponding valve was 
closed and that of the other set opened. 

Test-Seq was also used to sequentially measure CO2 
concentration at several places in the tunnels with 
the same infrared gas analyser.  The programme 
successively opened for a fixed time interval one 
of the six solenoid valves sampling the air in 
the tunnels.

Windmill Test-Seq is easy to use with no prior 
programming experience needed.  It simply 
interprets a text file of commands that are 
designed for data acquisition tasks.

Converting Analogue Measurements to Digital Values

The Microlink 751 captured the analogue measurements 
and converted them to digital values that could be 
stored by the computer.  Each 751 unit can capture 
data from 16 sensors and probes of various types.  
It can also switch digital outputs and hence could 
be used to control the solenoid valves according to 
the commands sent by the Windmill software.  

Further Reading

Aranjuelo, I., Irigoyen, J.J., Perez, P., 
Martinez-Carrasco, R. and Sanchez-Diaz, M. 2005.  
The use of temperature gradient tunnels for studying 
the combined effect of CO2, temperature and water 
availability in N2 fixing alfalfa plants.  Annals 
of Applied Biology 146: 51-60.

Perez, P., Morcuende, R., Martin del Molino, I. & 
Martinez-Carrasco, R. (2005) Diurnal changes of 
Rubisco in response to elevated CO2, temperature 
and nitrogen in wheat grown under temperature 
gradient tunnels.  Environmental and experimental 
botany, 53, 13-27.

Microlink 751 Unit

Windmill Software

or contact Windmill Software at [email protected]

Excel Corner

   "How do I combine stacked and clustered column 
    charts? Hope you can help!" 

This e-mail dropped through our mailbox last week, and 
solution wasn't as easy as we thought it would be.  A 
clustered column chart is the normal sort of column 
display, where each value is shown as a column.  The 
greater the value the higher the column.  Values across 
a row are shown side-by-side. 

A stacked column chart piles values from one row on 
top of each other, so you can compare the contribution 
of each value to the total. 

In Excel you can choose either type of chart, but it 
isn't straightforward to combine the two.  However, 
some clever souls have found a way round the 
problem. Unfortunately they all rely on your data 
being organised in a slightly peculiar way. If you 
want to give it a go then these pages each provide 
a solution.

Bernard Liengme's Excel Tips

Stephen Bullen's Excel Page,

AJP Excel Information

Microsoft's Support Site

Further Reading
For notes on combining scatter and stock charts see 
Monitor Issue 39

For more tips on using Excel see

Index to Articles Previously Published in Monitor

We published the first issue of Monitor
 in August 1998. 
Since then we have covered many issues relating to 
data acquisition and control.  For those who have not 
been with us throughout that time here is an index to 
our major articles.  And if you have been with us since 
1998: thank you very much! 

A/D Converters
A/D Converters
Abbreviations A-G
Abbreviations H-M
Abbreviations N-Z
Analogue Inputs
Analogue Outputs
Bottle Volume 
Brake Testing 
COM Port Settings
Connecting Equipment
Crash Testing 
DAQ Systems: choosing
DAQ Systems: choosing
Data Logging  
Data Logging Software
Data Logging Software
Data Logging Techniques
Dewpoint Temperature
Diesel Engine DAQ
Differential Inputs
Digital Outputs
Emission Monitoring
Emission Monitoring
Energy Monitoring
Engineering Units
Engine Testing
Fish Farming  
Fluorescence Mapping
Freezer Monitoring
Froude Consine Texcel
Handshaking RS232
HPIB Communications
Human Machine Interface
I2C Bus       
IMS Files     
Live News     
Logging Data  
Materials Testing
Mettler Toledo Balance
Modbus Communications
Modbus and Windmill
Molytek 2702  
Open Office   
Parallax BASIC Stamp
Parsing Data  
PID Control   
Pollution - Air
Pollution - Water
Powder Flow Rate
Process Mimic Design
Product Testing
Programming Tools
Quadra-Chek 2000
Rainfall Measurement
Relay Switching
Remote Sensing
Replaying Data
Resistance Measurement
RS232 Communications
RS232 Handshaking
RS232 Pins    
RS232 Troubleshooting
RS422 Communications
RS485 Communications
Satellite Navigation
Seabed Surveying
Serial Communications
Signal Conditioning
Simultaneous Sampling
Single-Ended Inputs
SI Units      
Strain Measurement
Switch Testing
Teacher Resources
Telemecanique Altivar
Temperature Accuracy
Temperature Measurement
Train Testing 
Transducer Monitoring
Transient Capture
Triggering Acquisition
Universal Serial Bus
User Interface Design
Utility Meter DAQ
VI Design     
Visual Basic  
Visual Basic  
Visual Basic  
Visual Basic  
Visual Basic  
Visual Basic  
Voltage Measurements
Waveform Generation
Weather Monitoring
Wide Area Networks
Wind Speed Measurement
Windmill Tips 
Wine Quality Control
Wireless Networks

* 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]


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