-------------------------Monitor------------------------ The Newsletter for PC-Based Data Acquisition and Control Issue 76 www.windmill.co.uk November 2004 --------------------ISSN 1472-0221---------------------- Welcome to the 76th issue of Monitor . Today we discuss how to log up to 200 data readings a second using Excel and our free Windmill software. We hope you enjoy the newsletter, but should you wish to cancel your subscription you can do so at http://www.windmill.co.uk/newsletter.html CONTENTS ======== * Windmill News: Seabed Surveying and Mapping * Excel Corner: Logging Data up to 200 Times a Second * Data Acquisition and Control Exhibitions ________________________________________________________ ________________________________________________________ Windmill News: Seabed Surveying and Mapping ________________________________________________________ At the University of Queensland's Zoology Department, they use a variety of different methods for seabed surveying and mapping. All of their surveys require GPS positions for each sample, so they can spatially analyse and present the data. The scientists needed some software to record positional data during sampling over a "track" (rather than "point" sampling). For instance: sampling by trawling, by "towed diver" visual surveys and by towed video surveys. The software they chose was Windmill. The great benefit of Windmill is that it is possible to record the "track" of each sample directly into Excel in real time. Once the sample is obtained (and its track recorded in Excel) they can enter observations and any other notes alongside the positional information for each sample, whilst still in the field. In all it saves a huge amount of time in writing and data entry, as well as preventing the problems of interpretation and mis-placing of data which sometimes occurred with the old practice of recording the information on sheets of paper. The ability to integrate other instrumentation such as echo sounders, water quality meters etc. offers further possibilities which the scientists plan to explore in the future. To use Windmill for this type of application you need its serial driver. Details of the latest version of this, COMIML, are at http://www.windmill.co.uk/https://www.windmillsoft.com/daqshop/rs232-modbus.html. Alternatively, as a subscriber to this newsletter you can download an older version (LabIML) for free. Further Reading =============== For more on Windmill software: http://www.windmill.co.uk/windmill.html Article on interfacing GPS Receivers: http://www.windmill.co.uk/gps.html ________________________________________________________ ________________________________________________________ Excel Corner: Logging Data up to 200 Times a Second ________________________________________________________ We've discovered that the example of how to use Excel to continuously log data, which we used to give on the web site, didn't work well if the sampling interval was less than once a second. We've therefore updated it to work properly at speeds of up to 200 readings (samples) per second. The new version is given below. Start displaying data in the Windmill DDE Panel program before running the macro. -- Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long) Sub SampleData() 'If NoOfRows = 1, the first data value 'will be placed in row 1. NoOfRows = 1 'Ask for number of sets of samples to be collected. NoOfSamples = Val(InputBox("Please enter no of samples to collect", "No of Samples")) 'Ask for the time to wait between taking each set of samples SamplePeriod = InputBox("Please enter sample interval in seconds", "Sample Interval") ' Convert to milliseconds - needed for sleep statement below. SamplePeriod = SamplePeriod * 1000 'Initiates conversation with DDE_Panel ddeChan = DDEInitiate("Windmill", "Data") 'Keeps conversation open until the required 'number of samples have been collected. While NoOfRows < NoOfSamples + 1 'Requests data from all channels and stores it in 'memory in an array called mydata. mydata = DDERequest(ddeChan, "AllChannels") 'Selects first sheet in currently selected workbook. Sheets("Sheet1").Select 'Ignores any warning messages which would halt the macro On Error Resume Next 'Finds the lower & upper boundaries of array, 'to determine the number of columns needed to 'store the data. Lower = LBound(mydata, 1) Upper = UBound(mydata, 1) 'Inserts data from the array into a row of cells. For Column = Lower To Upper Cells(NoOfRows, Column).Value = mydata(Column) Next Column 'Waits for the specified sample interval Sleep SamplePeriod 'Increments number of rows, so next set of samples 'is inserted in the next row down. NoOfRows = NoOfRows + 1 'Stops loop when required sets of samples collected. Wend DDETerminate (ddeChan) End Sub -- Changes Made to the Data Logging Macro ====================================== Instead of using "Wait" to pause the macro for specified logging interval, we've used "Sleep". So why did we use Wait in the first place? The macro was originally written for an early version of Excel, and the Sleep instruction wasn't available then. Note that Sleep isn't a standard Excel function. It is contained instead in a Windows DLL. So we need to tell the Excel VBA interpreter where the Sleep function can be found. This is done in the Declare statement: Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long) This tells VBA that the Sleep procedure can be found in kernel32.dll and that it expects a time in milliseconds as its parameter. Further Reading =============== For more on using Excel with Windmill see http://www.windmill.co.uk/excel/ ________________________________________________________ ________________________________________________________ Data Acquisition and Control Exhibitions ________________________________________________________ Continuing the quarterly list exhibitions around the world related to data acquisition and control. ISA Show South America 23 - 25 November Sao Paulo Brazil The major South American event in the automation, systems and instrumentation technology sectors. http://www.isashow.com.br/site/isashow_english/index.html Measurement Science Conference 17 - 21 January California USA Promoting education and professionalism in measurement science and related disciplines. http://www.msc-conf.com/msc/ MTEC 16 - 17 February 2005 NEC Birmingham UK The UK's national showcase for the sensor, measurement and instrumentation industry. http://www.mtec-info.co.uk/ National Manufacturing Week 7 - 10 March 2005 Chicago Illinois USA Includes industrial automation and design engineering. http://www.manufacturingweek.com/ OTOMASYON 17 - 20 March 2005 Istanbul Turkey Industrial automation fair. http://www.bilesim.com.tr/ AUTOMATICON 5 - 8 April 2005 Warszawa Poland International fair for measurement and control. http://www.automaticon.pl/ Interkama 11 - 15 April 2005 Hannover Germany The leading trade fair for process automation. http://www.hannovermesse.de/en/exhibition/trade-fair-line-up/industrial-automation/ Test and Measurement China 2004 12-15 April 2005 Shanghai China The exhibition encompasses test and measurement equipment such as meters, bare board testers, optical inspection system, circuit testers, x-ray equipment, test fixtures etc. http://www.nepconchina.com/ ________________________________________________________ ________________________________________________________ * Copyright Windmill Software Ltd * Reprinting permitted with this notice included * For more articles see http://www.windmill.co.uk 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 http://www.windmill.co.uk/newsletter.html and an index of articles at http://www.windmill.co.uk/newsletter.html 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] http://www.windmill.co.uk/ https://www.windmillsoft.com/
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