Windmill Software Ltd
Data Acquisition Intelligence

May 2011

The Newsletter for PC-Based Data Acquisition and Control
Issue 154            May 2011
--------------------ISSN 1472-0221----------------------

Welcome to Monitor, the newsletter for data acquisition 
and control.  In this issue we are pleased to offer you 
over 50% off our thermocouple monitoring and control 
package. Read below for full details or see

We also have a story on how a university and industry 
partnership has developed a technique for calibrating 
tension meters to improve mooring safety of oil rigs. 
They needed a data logging package which could handle 
load cells, motion sensors and a RTK receiver, and 
accept both ASCII and binary streams of data. Subscribers 
can download a trial of the Windmill software they used.

Finally check out our new Twitter account at where we'll be 
posting data acquisition news.

We hope you find the newsletter useful, but should you 
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go to 
Monitor Newsletter

* Windmill News: Half-Price Thermocouple Monitoring 
  and Control
* Calibrating tension meters to improve mooring safety 
  on semi-submersible oil rigs 
* Using Thermocouples in a Data Acquisition System
* DAQ News Roundup

Windmill News: Half-Price Thermocouple Monitoring and Control

This month we have reduced the price of thermocouple 
measurement and control from £730 to just £360 (425 Euro 
or 585 USD). The 751-TC package includes:
- Data acquisition and control unit which plugs into the 
  PC's USB port
- Windmill data logging, charting and control software
- Isothermal box 
- Technical support for life

With the 751-TC you can 
- Monitor 16 thermocouples or voltages 
- Count events with 8 counters
- Switch up to 32 digital outputs
- Monitor up to 32 digital inputs
- Connect 8 units giving 128 themocouple inputs and 
  256 digital inputs and outputs
- With extra hardware you can also monitor strain, 
  pressure and current
- Built-in linearisation for B, E, J, K, N, R, S and 
  T type thermocouples
- Choice of resolution from 12- to 18-bits
- Low power consumption: powered from the PC

When monitoring thermocouples it is essential that 
the system knows the temperature of one of the 
thermocouple junctions. Housing this junction in 
the isothermal box keeps the temperature constant, 
and a cold junction sensor in the box tells the 
system the temperature. Our isothermal box will 
also detect broken thermocouple leads for you. 

The digital outputs let you switch equipment on 
and off when readings cross alarm thresholds. A 
London hospital, for example, has used a 
Windmill 751-TC system to monitor the conditions 
of their low temperature liquid nitrogen 
freezers. Should any temperature cross an alarm 
threshold, a warning beacon outside the freezer 
room is switched on - alerting staff to 
the situation. 

For more information see, 
e-mail [email protected] or 
telephone +44 (0)161 833 2190.

Calibrating tension meters to improve mooring safety on semi-submersible oil rigs 

Catenary Testing Ltd have developed a technique for the 
calibration of tension meters to improve mooring safety 
on semi-submersible oil rigs. 

The method relies upon the fact that tight moorings allow 
less movement than slack ones. Following initial computer 
simulations, which proved the technical viability of the 
method, a scale model rig (see Figure 1 at was constructed for 
testing in the inner Moray Firth near Inverness. 

The data logging equipment present on the "mini rig" 
included a motion sensor, load cells connected to each 
anchor line and a RTK receiver. The bespoke loadcell 
circuit was designed to transmit data from the 
eight load cells at a rate of 8 Hz. The company therefore 
required a serial data logging application that was 
capable of receiving and processing that volume of data 
in addition to the data received from the RTK and 
motion sensor. 

After several unsuccessful trials with other serial 
data logging packages, they came across the Windmill 
website ( and purchased Windmill 7 
with the COMIML Serial Driver. They were able to use 
this software to parse the output strings of all 
data logging equipment on the rig. This was a great 
benefit as the RTK and motion sensor were transmitting 
ASCII characters, while the loadcell circuit was 
outputting binary strings. 

Another requirement was that the logged data was 
accurately timestamped. Other RS232 loggers looked 
at used the Microsoft Windows serial driver. This is 
incapable of logging data at the rate required, and 
is affected by other Windows processes running which 
can introduce varying delays to data acquisition. 
Windmill Software write all their own drivers, so the 
other benefit of Windmill was that it allowed them to 
log at the required rate and to precisely timestamp 
the data.

The data gathering phase of the project is now 
complete and the company have significant volumes of 
data to analyze and interpret in order to prove the 
theory in practice on a small scale. Early results 
look encouraging and the next stage is to test the 
technique on a full size, offshore moored installation.

The Windmill COMIML software - with logging, charting, 
display and control programs - is currently reduced to 
£50 from Windmill Software Limited at


Using Thermocouples in a Data Acquisition System

Thermocouples are widely used because they:
- are cheap
- can be glued to a variety of substrates 
- will withstand harsh environments
- cover a wide temperature range 
- have a fast response time owing to their small size

Thermocouples comprise two dissimilar metals joined 
together, making a continuous circuit. If one junction 
has a different temperature to the other, an electromotive 
force (voltage) is set up. This voltage varies with the 
temperature difference between the junctions. If the 
temperature at one junction (the cold junction) is known, 
the temperature at the other junction can be calculated.

Types of Thermocouple

There are several types of thermocouple, labelled with 
letters according to their constituent metals. A 
K-type thermocouple, for example, is made up of chrome 
and Alumel. The metals give the thermocouples differing 
properties, such as temperature range and accuracy.

Three Potential Pitfalls in a Thermocouple Monitoring System

1. Attaching the Thermocouples to Metal Surfaces
   If the thermocouples are directly attached to a metal 
   surface, particularly one carrying its own voltage such 
   as a heating element, you need to isolate the signals. 
   This will prevent high voltages in the monitored item 
   damaging the data acquisition equipment. It will also 
   make the measurements "float", letting you record the 
   small thermocouple voltage in the presence of 
   high voltages.

2. Linearisation
   The voltage produced by a thermocouple does not change 
   linearly with temperature - presenting a problem for 
   some data acquisition systems. Windmill will obtain the 
   correct temperature for you automatically in, say, 
   oC or oF, with built-in linearisation for B, E, J, K, 
   N, R, S and T type thermocouples.

3. Using the Wrong Type of Thermocouple Lead
   You need to connect the thermocouple to the 
   data acquisition unit using the correct type of 
   extension or compensating lead. This is made of either 
   the same material as the thermocouple metals, or 
   material with similar characteristics.

For more information on measuring temperatures with thermocouples, go to
To purchase a thermocouple monitoring system from 
Windmill, with over 50% off, go to

DAQ News Roundup

Welcome to our roundup of the data acquisition and 
control news.  If you would like to receive more 
timely DAQ news updates then grab our RSS newsfeed 
at  Read for notes
on how to display the live news on your own web site.

Researchers cancel SCADA hack talk 
   Siemens and the US Department of Homeland Security 
   asked researchers to cancel a conference demonstration 
   of how SCADA software could be hacked without the 
   backing of a nation state.  The presentation was due 
   to demonstrate how traditional exploits could be 
   harnessed to carry malicious code and how that code 
   could be developed without direct access to the target 
   hardware, in particular the Siemens WInCC PLC.
   Source: The H Security

The Secret Behind NIST's New Gas Detector
   Trace gas detection, the ability to detect a scant 
   quantity of a particular molecule-a whiff of 
   formaldehyde or a hint of acetone-in a vast sea of 
   others, underlies many important applications, from 
   medical tests to air pollution detectors to bomb 
   sniffers. Now, a sensor recently developed at the 
   National Institute of Standards and Technology (NIST) 
   that is hundreds of times faster and more sensitive 
   than other similar technologies may make such detectors 
   portable, economical and fast enough to be used everywhere.
   Source: National Institute of Standards and Technology

Software helps cut energy use by quarter
   A software engineering student from Portsmouth has 
   helped design a new way of cutting energy use in 
   buildings by up to 25 per cent.
   Source: Portsmouth University

Scientists extend the battery life of forest climate monitors
   Scientists in Germany have boosted the life of 
   wireless sensors designed to protect forests by 
   monitoring their climate conditions.
   Source: The Engineer

* 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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