------------------------Monitor------------------------- The Newsletter for PC-Based Data Acquisition and Control Issue 47 www.windmill.co.uk June 2002 --------------------ISSN 1472-0221---------------------- Welcome to the Monitor newsletter. In this issue an experience from Windmill Technical Support illustrates how to configure Windmill software for a variety of requirements. We only send this newsletter to people who have subscribed - should you wish to cancel your free subscription please do so at http://www.windmill.co.uk/newsletter.html CONTENTS ======== * Windmill News: Technical Support for Custom PLCs 1-Identifying the start of a message 2-Triggering messages and extracting data 3-Setting up Windmill 4-PLC data into Excel 5-Opening a Windmill Logger File * Data acquisition and control exhibitions ________________________________________________________ ________________________________________________________ Windmill News: Windmill Used to Read Custom Logic Controller ________________________________________________________ Recently a Windmill customer wanted to use Windmill and COMIML to get data from a custom logic controller, log the data and pass it to Excel for on- and off-line analysis and display. The application posed a number of problems which provide a good illustration of how you can configure the software for particular requirements. COMIML COMIML is a generic driver which lets you acquire data from almost any serial device. For more details of COMIML see https://www.windmillsoft.com/daqshop/rs232-modbus.html The Custom Programmable Logic Controller The logic controller output a set of binary and hexadecimal data values packed as 4 bytes of data every few seconds. * Problem 1: Identifying the Start of a Message ============================================= There is no specific start character in the 4-byte message sent by the PLC. This means that when COMIML starts running in the PC it cannot identify the beginning of a message and might pick-up any of the 4 bytes as its first character. It would then continue to try to parse data values from subsequent messages, but the bytes would be out of sequence and the data values extracted therefore wrong. Solution: Rather than increase the number of data bytes sent by the controller, the user decided to modify the controller software so that it started a new message whenever it received a command from the computer. The command to get a set of data would be a single character. COMIML would then parse the next 4 bytes received from the controller. * Problem 2: How to Trigger the Message and Retrieve Data ======================================================= The user next wanted to know how to use Windmill to send the character to prompt the PLC to transmit its message, and how to parse the received message and extract the data Solution: The COMIML driver is configured using the free ComDebug communications software. (You can download this from https://www.windmillsoft.com/daqshop/rs232-modbus.html). The user started ComDebug and selected to create a new Windmill Instrument file. He would later save this for use with the other Windmill programs. He didn't need an "initialisation message" so chose to add a completely new message. The Send or Prompt part of this was the single character to trigger a set of data. When this was sent, the 4 bytes were returned as the Reply message. The Parse option in ComDebug was then used to: - Extract individual bits from the first two bytes - Extract hexadecimal numbers from the last two bytes. Each of these was associated with a channel of data. The channels are initially numbered from 0 up, but can be given names if required. When extracting bits, the bit number in the byte is entered as a parameter, with bit 0 being the least significant bit (i.e. the right hand bit when expanding a character byte into bits). The setup was tested to check that when the Prompt character was sent the correct Reply message came back and was parsed successfully into the various channels. The Windmill Instrument file was then saved as an *.imd file. Back at the opening screen of ComDebug, there is an option to Edit Windmill Device. By clicking on this the user added his *.imd file to the list of devices which Windmill will associate with the COMIML driver. As several .imd instrument files can be saved, COMIML can be configured for many different devices. * Problem 3: Setting up Windmill to use the *.imd File ==================================================== When you install Windmill it always inserts the Software Signal Generator as the default driver or handler. The purpose of the driver is to handle communications with the hardware collecting the data. The Software Signal Generator creates its own data values internally and you can therefore use it to try out Windmill applications without the need for any data acquisition hardware. However, the user wanted instead to have COMIML as the default driver. Solution: 1. Having earlier installed the Windmill programs and then the COMIML driver, there will have been the opportunity to change the drivers loaded for Windmill applications. If you do not change anything during the installation, the Software Signal Generator will be selected. However, you can later change the drivers - see step 2. 2. Run the Windmill program ConfIML. This shows you which drivers will be loaded for the Windmill programs - you can click Remove to clear out the Software Signal Generator (and any others you do not require), and then click Add to select from a list of installable drivers. For RS232 instrument applications, select COMIML. This will be associated with the *.imd file because of the action taken to edit the Windmill Device earlier. The COMIML instrument file will be loaded as device 0 (if it is first on the list of drivers). 3. Run the Windmill program SetupIML. The COMIML driver should be loaded as an icon in the task bar, and the screen should show the number of channels you have previously defined using ComDebug. You can use SetupIML to name the channels for Windmill use. Save the setup you have created with SetupIML. 4. Run the Windmill DDE Panel program, WmDDE. Select the setup file you just created then select all the channels. The data from the controller should now start appearing in the DDE Panel. Once the data starts appearing in DDE Panel, communication has been established with the controller. If any items of data have been missed or parsed wrongly they can be modified by going back to ComDebug and editing the existing Windmill Instrument file. * Problem 4: Getting Data into Excel ================================== Next the user wanted to get data into Excel. He wanted to display it there in hex format as it appears on his LED displays associated with his controller. Solution: Clicking the Copy to Clipboard button in DDE Panel updated the Windows clipboard with the current data. In Excel, an area of cells to receive the number of data channels was then selected. From Excel's Edit menu, "Paste Link Special" placed the updating data values in the cells. To further analyse the data values as they come in, using VBA, see the sample DDE code on the Windmill web site at http://www.windmill.co.uk/excel/ * Problem 5: Opening a Windmill Logger File ========================================= The user found Windmill Logger to be useful to view data, but was unsure of how to get back the data once it had been saved to disk. Solution: The logged data is stored in ASCII format, and so he could use Windows Notepad to open and view the *.wl file created by Windmill Logger. This quickly confirmed that data has been collected. The Logger data files are tab separated, and depending on the length of the data values for each channel, a neat tabulation of the data may not be possible with Notepad (the tab settings being too close together). For further analysis or report generation the Logger data file can be read into Excel. Using File.Open in Excel, and selecting the option for all files, the *.wl file can be loaded. Excel will recognise this as a tab separated value file and the default options offered by the spreadsheet for interpreting the structure can be used. * We hope you found this problem solving experience from Windmill Technical Support useful. If you would like help with your application: Fill in the form at the bottom of http://www.windmill.co.uk/faq.html Ring +44 (0)161 833 2782 or E-mail [email protected] Don't forget that a complete guide to using each of the Windmill programs appears when you choose the Help item on the program's menu bar. The latest version of the Help files are free from http://www.windmill.co.uk/help.html ________________________________________________________ ________________________________________________________ Exhibitions and Conferences ________________________________________________________ Every other month we list forthcoming exhibitions and conferences related to data acquisition and control. Control & Instrumentation Asia 9-12 July Singapore Part of PSA 2002, the exhibition runs alongside Watertec, Envirotec, Chemtec and Motion, Drive & Automation. http://www.psa2002.com/main.htm IEEE AutotestCon 2002 21-24-August Huntsville Al USA Conference focusing primarily on automated test and related technology for military, government and aerospace applications. http://www.autotestcon.com/ Scanlab 2-5 September Bella Center Copenhagen Denmark Fair and conference for laboratory equipment, measuring technology and process control. http://www.scanlab.dk/ Instrumentation Scotland and Offshore Systems 4-5 September Aberdeen UK http://www.instrumentation.co.uk/ ATDC 2002 12-14 September Slavonski Brod, Croatia A European forum to exchange scientific, technology and manufacturing knowledge between Western Europe and Central and Eastern Europe. Topics include product development, production technologies, information technology, quality assurance and measurement. http://www.sfsb.hr/atdc2002/atdc2002.html Sensors Expo 23-26 September World Trade Center Boston USA Brings together the technologies that are shaping sensing, data acquisition, control and communications. http://www.sensorsexpo.com/ Wescon North America 24-26 September Anaheim Convention Center California USA Exhibition including test & measurement and hardware & software design. http://www.wescon.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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