-------------------------Monitor------------------------ The Newsletter for PC-Based Data Acquisition and Control Issue 115 www.windmill.co.uk February 2008 --------------------ISSN 1472-0221---------------------- Thanks very much if you completed our survey last month. This month we've another request. If you are logging data from an instrument connected to your PC over RS232, could you email us an example of the data string sent by the instrument? We are planning a feature to help readers acquire data from their measuring devices. Thanks. I hope you enjoy the newsletter but if you want to remove yourself from our mailing list please do so at http://www.windmill.co.uk/newsletter.html CONTENTS ======== * Windmill News: Survey Results * Windmill Notes: Connecting a Garmin GPS to a PC * Excel Corner: Conditional Counting - COUNTIF * DAQ News Roundup ________________________________________________________ ________________________________________________________ Windmill News: Survey Results ________________________________________________________ Last month we asked you some questions to try to improve Monitor and our service. Thank you very much for your answers and comments. If you didn't complete the survey but would like to do so, go to http://www.windmill.co.uk/monitor114.html One reader suggested it would be helpful if we provided a list of instruments and their message strings. To do this we need your help - please could you send us an example of your instrument's data string and the name of the instrument? E-mail to [email protected] We had several requests to cover topics which we have already visited. We've thus put up a comprehensive index to back issues at http://www.windmill.co.uk/monitorindex.html. I hope you find it useful. More people preferred a text format newsletter to one in HTML format (47% to 39% with 14% not being bothered either way). The text format was thought to be good because it made the newsletters "easy to save" and "quick and small". Over 93% of you were very or fairly interested in the Excel Corner, real-world examples of how Windmill software is being used, tips on using Windmill and the articles on data acquisition. So we shall be including more of these types of story in future issues. Thanks very much for your input. E-mail any other questions, comments or suggestions to [email protected] ________________________________________________________ ________________________________________________________ Windmill Notes: Connecting a Garmin GPS Receiver to a PC ________________________________________________________ Note: the software used in this example has been replaced by Windmill 7. See our new instructions on connecting a Garmin GPS here. Windmill lets you log data from a Garmin GPS Receiver to your PC. Subscribers to Monitor can download a free copy of Windmill 4.3. Alternatively you can purchase Version 6 of Windmill from https://www.windmillsoft.com/daqshop/rs232-modbus.html There are three basic steps to starting to log data from a GPS receiver using the free software. 1. Run the Windmill ConfIML program and enter your GPS's communication settings. 2. Run the Windmill SetupIML program and choose names and units for your GPS data. 3. Run the Windmill DDE Panel or Logger program to display or save data from your GPS. Once you have configured the Windmill software you can in future go straight logging data. * Windmill ConfIML ================ This program detects and saves a record of the hardware you want to use, in our case a Garmin GPS receiver. The settings below work with most Garmins, but check your Manual to make sure. 1. Start ConfIML and Press the Add button. 2. Select LabIML RS232 ASCII Instrument Handler. 3. Type a name for the Garmin, a description and enter how many channels of data you will be collecting (two if you are just recording latitude and longitude). Press OK. 4. Enter your instrument's settings: - Reading Protocol: Continuous Flow - Instrument Idle or Wait Time: 0 - Data Persistence: 5000 (assuming you are taking readings more often than once every 5 seconds) - Returned Message Length: 100 - Instrument Initialisation String: Leave blank 5. Press the Channels button. Enter the instructions to extract the reading from the string of data sent by the GPS. This is called the Reply Parse String. - The Garmin sends many different types of messages, for example $GPRMC,hhmmss,A,llll.ll,N,yyyyy.yy,W,kk.k,tt.t,ddmmyy,mm.m,W*CS Here llll.ll is the latitude and yyyyy.yy is the longitude. - to extract the latitude you could Search for "$GPRMC", Ignore 10 characters then Extract everything until the next comma. This appears as \S"$GPRMC"\I10\E"," - to extract the longitude you could Search for "N,", Extract until the next comma. This appears as \S"N,"\E"," Note: in this example your Latitude channel must come before your Longitude channel. For example, channel 0 is Latitude and channel 1 is Longitude. This is because it is the Latitude channel which pinpoints the correct place in the data string to start (ie at the beginning of the $GPRMC sentence). 6. Enter the communications settings being used by the Garmin. For example... - Baud: 4800 - Data Bits: 8 - Parity: None - Flow control: None 7. Save your settings and close ConfIML. You may receive a message asking you to restart Windows. Ignore this but be sure to close any IML or Windmill icons on the Taskbar. You can now start SetupIML. * Windmill SetupIML ================= With the SetupIML program you can name channels, set units and so on. 1. Choose to Create a New Setup and enter a name and description. This can be anything you like. 2. From the Device menu select LabIML. 3. Your data channels will be shown as a numbers like 10000, 10001. Double click a channel number. 4. Type name for your channel, eg Lat, and make sure Enable for Input is checked. 5. Save your settings in a *.ims file, close SetupIML and run DDE Panel or Logger * Windmill DDE Panel ================== 1. From the File menu select Load Hardware Setup and choose the *.ims file you just saved. 2. Connect your GPS channels. You should see your co-ordinates in DDE Panel. 3. Proceed similarly for the Logger program. * Getting the data into Excel or Mapping programs You can use the Windmill Logger program to collect data, and after collection has finished import it into Excel or your mapping program. Alternatively, you can collect data with Excel in real-time by writing an Excel macro to read data from the Windmill DDE Panel. For more details see our Excel page at http://www.windmill.co.uk/excel/ * Trouble-Shooting ================ If you are having problems receiving data from your Garmin GPS receiver, right-click the LabIML icon on the tool bar and select "Debug Options". If the LabIML Debug window says "Parsing Failed", go back to the ConfIML program and edit your Reply Parse String. If no data is shown in the LabIML Debug window, you may have a communication or a cabling problem. Check your settings in ConfIML - baud rate etc - correspond to those being used by the GPS. If so make sure your cable is compatible with Garmin. Should your PC not have any RS232 ports you can purchase a USB-Serial cable. If you still have problems fill in the form at http://www.windmill.co.uk/garmin.html * Further Reading: ================ Interfacing a Garmin GPS Receiver (includes screenshots) http://www.windmill.co.uk/garmin.html Monitor #52 - Interfacing NMEA Instruments http://www.windmill.co.uk/monitor52.html Monitor #44 - Geographical Information Systems http://www.windmill.co.uk/monitor44.html ________________________________________________________ ________________________________________________________ Excel Corner: Conditional Counting - COUNTIF ________________________________________________________ Excel's COUNTIF function is often useful when analysing your data. Here are a couple of examples: they both are being applied to a column of data in cells B2 to B100. To count the number of negative readings =COUNTIF(B2:B100,"<0") To count the number of readings which are between 17 and 18: =COUNTIF(B2:B100,">=17")-COUNTIF(B2:B100,"<18") * Using the Functions in your Macros ================================= You can use COUNTIF in your VBA code. Here we are counting the number of negative readings and storing the result in a variable called BelowFreezing. BelowFreezing = Application.COUNTIF(Sheets("Sheet1") .Range("B2:B100"), "<0") * Counting over Scattered Cells ============================= The COUNTIF function checks to see if the specified cells meet one condition. You can use cell references as in our example, or a named range. The range of cells can spread several rows and columns, but must be contiguous: =COUNTIF(A2,A4,A6,"<0") won't work. However, you can sum COUNTIF functions to get the required result. =COUNTIF(A2,"<0")+COUNTIF(A4,"<0")+COUNTIF(A6,"<0") * Having a Cell Contain the Condition =================================== In our examples we have entered our conditions as numbers. You could instead use a cell reference. In this example the cell C1 holds the numerical part of the condition (the operand). =COUNTIF(A2:A100,"<"&C1) Note the less than symbol is enclosed in inverted commas and the & sign which precedes the cell reference. * Counting against more than one Condition ======================================== With COUNTIF you cannot count against more than one condition: such as the number of times both the temperature was over 0 oC and the humidity was below 50%. Instead you could use DCOUNT, an array formula or a Pivot table. More on these in future issues. For more tips on using Excel for data acquisition and analysis see http://www.windmill.co.uk/excel/ and http://www.windmill.co.uk/excel/excel-charting.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 http://www.windmill.co.uk/newsfeed.php for notes on how to display the news on your own web site, read it via e-mail, mobile phone or a newsfeed viewer. Divers make precision measurements A new underwater sensing device can operate at depths of 25 m. The device can accommodate pH, oxygen and hydrogen sulphide microsensors. The system can be pre- programmed to autonomous operation or interactively operated by SCUBA divers. Internal batteries supply power for up to 24 hours of measurements, storing up to 64 million data samples. Source: SCUBA Diving News http://news.scubatravel.co.uk/ Position sensors: magnets know their place Non-contact position sensors are small but important parts of many modern machines. Researchers have used a phenomenon known as magnetoresistance to develop a practical, low-cost position sensor that performs better than existing designs. Source: CORDIS http://tinyurl.com/2wajy7 Cyclists' cellphones help monitor air pollution Cellphones used by bicycle couriers are monitoring air pollution in Cambridge, UK, and beaming the data back to a research lab. The technique is made possible by small wireless pollution sensors and custom software that allows the phones to report levels of air pollutants wherever they happen to be around town. Source: NewScientist.com https://www.newscientist.com/ NMR on a Chip A super-sensitive mini-sensor developed at the National Institute of Standards and Technology (NIST) can detect nuclear magnetic resonance (NMR) in tiny samples of fluids flowing through a novel microchip. The prototype chip device may have wide application as a sensitive chemical analyser. Source: NIST https://www.nist.gov/ Industrial Control Shipments Strong in 2007 US industrial control shipments surged 8.3 percent in the fourth quarter of 2007, but a darkening economic outlook may weigh on future demand - according to electrical equipment association NEMA. Source: NEMA http://www.nema.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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