-------------------------Monitor------------------------ The Newsletter for PC-Based Data Acquisition and Control Issue 154 www.windmill.co.uk 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 https://www.windmillsoft.com/daqshop/thermocouple-measurement.html 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 http://twitter.com/DataAcquisition where we'll be posting data acquisition news. We hope you find the newsletter useful, but should you wish to remove yourself from our mailing list please go to Monitor Newsletter CONTENTS ======== * 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 https://www.windmillsoft.com/daqshop/thermocouple-measurement.html, 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 http://windmill.co.uk/loadtest.html) 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 (windmillsoft.com) 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 https://www.windmillsoft.com/daqshop/rs232-modbus.html ________________________________________________________ ________________________________________________________ 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 https://www.windmill.co.uk/temperature.html To purchase a thermocouple monitoring system from Windmill, with over 50% off, go to https://www.windmillsoft.com/daqshop/thermocouple-measurement.html ________________________________________________________ ________________________________________________________ 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 https://www.windmillsoft.com/monitor.xml. Read https://www.windmill.co.uk/newsfeed.php 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 http://www.h-online.com/ 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 https://www.nist.gov/pml/div685/chirp-051011.cfm 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 http://www.port.ac.uk/ 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 https://www.theengineer.co.uk/ ________________________________________________________ ________________________________________________________ * Copyright Windmill Software Ltd * Reprinting permitted with this notice included * For more articles see https://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 https://www.windmill.co.uk/newsletter.html and an index of articles at https://www.windmill.co.uk/monitorindex.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] https://www.windmill.co.uk/ https://www.windmillsoft.com/
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