-------------------------Monitor------------------------ The Newsletter for PC-Based Data Acquisition and Control Issue 96 www.windmill.co.uk July 2006 --------------------ISSN 1472-0221---------------------- Welcome to the latest issue of Monitor. We hope you enjoy it, but should you wish to cancel your subscription you can do so at http://www.windmill.co.uk/newsletter.html CONTENTS ======== * Windmill Notes: Charting Data * Why and When to Calibrate Instruments * DAQ News Roundup ________________________________________________________ ________________________________________________________ Windmill Notes: Charting Data ________________________________________________________ When you download the free Windmill package, or buy Version 6 of the software, you will find a charting program included in the bundle. This is called "Windmill Chart". Chart handles many types of input channel, from many types of devices and sensors, including: thermocouples, pressure transducers, digital switches, flow meters and almost any laboratory instrument with an RS232 port. To use Chart you just select up to 8 channels of data then click the Start button. If you need to see more than 8 channels, just start another instance of Chart. You can chart the same channel in two Chart windows, each running at different speeds. This lets you see a detailed short term view in one while the other tracks a long term trend. When doing this it often helps to change the title of the Chart window from "Windmill Chart" to something more descriptive. To do this stop the chart then select Display from the menu bar. Chart's Print option only lets you print a static chart. However, if you want a copy of a moving chart just Press Alt + PrintScreen. This will copy the chart to the clipboard from where you can paste it into your document or spreadsheet. There are various styles of chart: separated or super-imposed traces; grid-lines on or off; choice of pen colour for each channel; black or white background; alarm indication; and so on. You set these from Chart's Display menu. Windmill Chart shows alarm levels as tick marks on its axis. It can also show its traces in different colours for no alarm, warning alarm and critical alarm states. Other Windows applications can send commands to Chart by means of Dynamic Data Exchange (DDE). For example, you could use Excel or a Visual Basic program to start, stop and print the chart. See Chart's Help file for the full list of commands it understands and information on dynamic data exchange. You can download the latest versions of the Help file from http://www.windmill.co.uk/help.html Chart shows a continuously updating graph of live data against time. If you want to replay previously logged data as a moving chart you need the Windmill Replay program. This will re-run the data and lets you fast-forward, rewind and zoom in and out. It also display a table of data that, when you double-click a point on the chart, shows you the exact value of that point. For more on Replay see http://www.windmill.co.uk/replay.html For more on Windmill Chart and the other Windmill software see http://www.windmill.co.uk/chart.html http://www.windmill.co.uk/windmill.html If you prefer to use Excel to chart your data see http://www.windmill.co.uk/excel/excel-charting.html ________________________________________________________ ________________________________________________________ Why and When to Calibrate Instruments ________________________________________________________ Measurement and control devices are sold tested and calibrated to international standards. Over time, though, they will lose their accuracy and measurements will "drift". Drift is a slow variation of a performance characteristic such as gain. Drift is due to component ageing or environmental changes: for example changes in temperature or humidity. It is especially significant when you are measuring low-level signals (a few microvolts) over long periods of time, or in difficult environmental conditions. The way to deal with drift is to re-calibrate the instrument periodically. Calibration compares the instrument's actual performance to an accuracy standard. To do this you may need to return the instrument to the manufacturer or receive an on-site visit from them. You will then receive a calibration certificate which will be valid until the next recommended calibration date, often a year later. The higher the accuracy required, the more frequently the instrument will need to be calibrated. Some instruments are able to re-calibrate themselves periodically. They measure a reference voltage and compensate for offset and gain drifts. An offset drift results in a reading other than zero, for a zero condition. Self-calibration is useful for long term monitoring since drifts do not accumulate. You need to be careful not to set the re-calibrations too far apart as this can lead to small discontinuities in the recorded data as the re-calibrations occur. Further Reading =============== Issue 95 of Monitor, Choosing the Right Range and Resolution http://www.windmill.co.uk/monitor95.html#range Data Acquisition Glossary http://www.windmill.co.uk/glossary.html ________________________________________________________ ________________________________________________________ DAQ News Roundup ________________________________________________________ Welcome to our roundup of the latest findings in data acquisition and control. If you would like to receive more timely DAQ news updates then grab our RSS newsfeed at https://www.windmillsoft.com/monitor.xml. Read http://www.windmill.co.uk/newsfeed.php for information how. Tiny radio chip can store video clips A memory device the smaller than a grain of rice has been developed by Hewlett Packard Labs. Called the Memory Spot, the chip makes it possible to attach digital information to any surface, object or document. So a postcard could be accompanied by photos or videos. The chip is a read-write CMOS memory device, 2-4 mm square, with a built-in antenna and 10 ten times faster than Bluetooth. Source: Hewlett Packard http://www.hp.com/ Device records smells to play back later Engineers at the Tokyo Institute of Technology in Japan are building an odour recorder capable which will record a smell and play it back later. The system will use 15 chemical-sensing microchips to pick up a broad range of aromas. These are then used to create a digital recipe from a set of 96 chemicals that can be chosen according to the purpose of each individual device. Source: New Scientist http://www.newscientisttech.com/ Noise Measurement May Boost Wireless Device Performance Researchers have developed improved methods for accurately measuring very faint thermal noise caused by random motion of electrons in electronic circuits. The technique may help improve the signal range, data rate and battery life of wireless devices. Source: National Institute of Science and Technology https://www.nist.gov/ Call for Proposals on Standards for Wireless Automation ISA's standards committee on wireless systems for automation has issued calls for proposals to encourage a variety of experts to collaboratively create a new series of wireless communication standards for industrial monitoring and control. Source: ISA - The Instrumentation, Systems, and Automation Society https://www.isa.org/ ________________________________________________________ ________________________________________________________ * 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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