PLC Excel
December 2002

The Newsletter for PC-Based Data Acquisition and Control
Issue 53       December 2002
--------------------ISSN 1472-0221----------------------

Welcome to December's issue of Monitor
 and our 
complements of the season to you.  We only send this 
newsletter to people who have subscribed - should you 
wish to cancel your free subscription please do so at

* Windmill News: New Strain Measurement Package
* Excel Corner: Tips on Naming Ranges
* Exhibitions of Data Acquisition and Control

Windmill News: New Strain Measurement Package

Our on-line catalogue now features a complete strain 
measurement system.  The Windmill 751-SG package 
comprises a USB data acquisition and control unit, signal 
conditioning and our Windmill software.

The USB unit provides differential inputs to monitor 16 
strain gauges or voltage signals.  Connect 8 USB units to 
1 PC and monitor up to 128 strain gauges.  The units also 
provide digital input and output and counting.

Strain gauges need an external excitation to supply 
sufficient current to keep all the bridge circuits 
energised.  The 751-SG package provides four sets of 16 
screw terminals giving + and - excitation and signals for 
each of 16 bridges. 

When a bridge input is selected the Windmill software 
automatically monitors excitation voltage and performs 
the bridge calculation to produce a reading in 
microstrain.  This eliminates errors due to changes in 
excitation voltage, especially important in long-term 

The changes in voltage due to strain are tiny: measured 
in microvolts. Monitoring such small signal changes can 
often produce jitter in the readings from noise. The  
751-SG package counteracts this with an integrating 
analogue-to-digital converter. By averaging the signal 
over 50 or 60 Hz the noise is rejected. 

The initial unstrained bridge measurement is often much 
larger than the change in signal due to strain. If this 
initial value is not accounted for, it restricts the 
resolution you can obtain - i.e. the smallest signal you 
can measure. The Windmill software lets you zero or 
balance the bridge, nulling the offset of the initial 
voltage. So instead of measuring over a wide range, 0 to 
0.5 V for example, you can choose a narrow range such as 
-0.01 to 0.01 V. 

The modular Windmill software suite offers data logging, 
charting, alarm indication, output control and DDE links 
to other applications like Excel.  You can also add 
process mimic generators, sequence control and many other 

The strain measurement system costs 875 UK pounds.  For more information see
or contact

For a tutorial on measuring strain visit

Excel Corner: Tips on Naming Ranges

Giving a range of cells a meaningful name, rather than 
referring to, for example A1:C7, can make spreadsheets 
much easier to understand, use, edit and trouble-shoot. 
Naming ranges within Excel is a very simple process that 
allows us to change the way 
we read formulas.  Instead of having a formula read
=E1*E2 where E1 may store the formula to convert Celcius to 
Fahrenheit, and E2 a temperature reading in Celcius, we 
might use named ranges to make our formula look like 


Naming Ranges - The Basics

To name a range in Excel is very easy, but there are a 
few rules to adhere to:

1. The first character of a name must be either a letter 
   or the underscore (_) character.

2. We cannot give a cell the same name as an existing cell 
   reference, for example B22 or R22C2.

3. Spaces are not allowed, but this can be overcome 
   by using the underscore (_), full stop  (.) or 
   capitalising the first letter of words.

4. Names cannot exceed 255 characters.

5. If a name contains more than 253 characters, we will 
   not be able to select it from the Name Box.

6. Names are not case sensitive (c_to_f is the same as 

7. All named ranges are absolute by default, for example 

To name a range in Excel you simply select the cell or 
cells to which you wish to apply a name, and click the 
top of your screen immediately to the left of your 
formula bar in what is called your Name Box.  This  
highlights the active cell address which you can then 
type over.  Type the name that you wish to apply  and 
press the Enter key on your keyboard.  

From now on, no matter where you are in your Workbook, 
you will be able to click the drop arrow to the right of 
the Name Box and see a list of all named ranges.  Click 
the one you require and you will be taken to that 


Replacing Cell Addresses With Names In Existing Workbooks

If you have already set up your workbook with a multitude 
of formulas referencing only cell addresses, and you decide 
that you should name your ranges but cannot face the task 
of manually going through changing all cell references, 
don't despair because Excel has made this extremely easy.

Don't be tempted to use Excel's Edit>Replace feature this 
could cause all sorts of problems.  Here is the correct 

1. Select any cell on the worksheet.

2. Go to Insert>Name>Apply

3. Select the names you wish to use in place of 

4. Click OK.

If you now click back in any cell that was previously 
referencing a cell address, you will see that Excel has 
automatically replaced all cell references with named 


Deleting or Modifying Named Ranges

To delete or modify a Named Range, go to 
Insert>Name>Define or (Ctrl+F3).  Once here you simply 
select the name you wish to delete and click Delete.  

If you want to modify to where the Named Range 
refers, simply select its name, alter accordingly in the 
Refers to: box at the bottom, then click Add.


This article was adapted from the original by Ozgrid 
Business Applications.  Ozgrid are specialists in 
distance online Excel and Excel VBA training, plus 
worldwide sellers of Excel add-ins and business software.  
Their website offers many more Excel tips and tricks -

For tips on using Excel with Windmill see


Exhibitions and Conferences

Every other month we list forthcoming exhibitions and 
conferences related to data acquisition and control.

12-13 February
NEC Birmingham UK
British event dedicated to sensors, measurement and 
instrumentation. This year features the Sensor 
Engineering Forum which includes free workshops.

Machine Building
12-13 February
NEC Birmingham UK
Exhibition for machine building, automation and design. 
Includes sensors, control equipment, motors, displays, 
keyboards, switches, enclosures and cabinets, barcode 
readers and electrical components.

Southern Manufacturing and Southern Electronics
19-20 February
Thorpe Park Surrey UK
Covers engineering design, production, plant and 

Electronic House Expo
26 February - 1 March
Orange County Convention Center Orlando Florida USA
Product demonstrations and seminars on home networking, 
automation, entertainment and security.

Midlands Manufacturing
19-20 March
NEC Birmingham UK
Latest developments and technology in subcontract 
assembly, automation, fabrication, packaging, labelling, 
materials, CAD/CAM & IT, inspection and electronic 

25-28 March
Paris Expo, Porte de Versailles Paris France.
Focuses on design, systems integration, production, test 
and measurement.

* 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)161 834 6688
Facsimile: +44 (0)161 833 2190


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