TR11-211 - Faculty of Computer Science
Contents
1. 6 Usage and documentation You only have to import in your program the uspp module and automatically it loads the correct classes for the platform in which you are running the program First of all you have to create a SerialPort object with the settings you want If a SerialPortException is not generated then you just can use the read and write methods of the object to read and write to the serial port Example gt gt gt from uspp import gt gt gt tty SerialPort COM2 1000 9600 gt gt gt Opens COM2 at 9600 bps and with a read timeout of 1 second gt gt gt tty write a Writes a character to the COM2 port gt gt gt Now suppose we receive the string abc gt gt gt tty inWaiting gt gt gt tty read gt gt gt tty inWaiting gt gt gt tty read 2 bc Documentation of the different classes and methods can be found on uspp module docstring 13 B Example of a Kermit Input File This is the input file used to run Kermit it contains the list of the commands to be executed on the serial port SET MODEM TYPE NONE SET LINE dev ttyUSBO IF FAIL EXIT 1 Device not available SET SPEED 9600 SET FLOW CONTROL RTS CTS SET INPUT ECHO ON set carrier watch off OUTPUT INPUT 3 OK OUTPUT D3 13 INPUT 3 OK OUTPUT M4 13 INPUT 3 OK OUTPUT Q 13 INPUT 3 OK exit 14 C WindSonic Command Description These commands are only for the polled mode as explained in the WindS2. break command command r try Send the bytes corresponding to the string entered by the user out write command getBytes System out println Written catch Exception e e printStackTrace try Sleep a prudential time to wait for the WindSonic answer Thread sleep 2000 catch Exception e System out println Sleep error Shows to the user the availabre number of chars to be read the user should select a less or equal number of bytes to avoid blocking System out print Chars available to read System out println in available System out print Enter number of Chars to read command user readLine int num Integer parseInt command Read the number of chars selected by the user for int i 0 i lt num i char c char reader read System out print c System out println Program closed catch Exception ex ex printStackTrace 20
3. the sensor reads the command D3 r and answers correctly 3 Kermit The command kermit input txt gt output tct was used to call Kermit with the commands on the input file and get the responses written to an output file An example input file for Kermit is shown in appendix B The use of Kermit gave the same problem of reading only every second character that was found with the USPP Python library when trying to execute any command from the polled mode In summary changing configuration and polled mode works fine with minicom but not with Ker mit and Python Both Kermit and Python require extra characters in even positions to get the WindSonic to correctly accept polling and configuration commands in polled mode The following steps were carried out to compare Minicom and the USPP Python library Minicom Python gt minicom gt python2 7 gt gt from uspp import gt gt tty SerialPort dev ttyUSBO 1000 9 600 To Enter Configuration Mode from Continuous Mode gt Enter gt gt tty write In Configuration Mode To check settings To check settings gt D3 Enter gt gt tty write D3 r To switch to polled mode To switch to polled mode gt M4 Enter gt gt tty write M4 r To return to measurement mode To return to measurement mode gt Q Enter gt gt tty write Q r In Polled Mode To activate mode To activate mode gt Enter gt gt tty write To ask node ID To ask node ID gt amp gt gt t
4. middle 111Text 90 650 300 textAlign center textBaseline middle f il1Text 270 140 300 17 var radius 225 var centerX 400 var centerY 300 Initiates the Canvas element var canvas document getElementById element var elem canvas getContext 2d drawCircle drawLetters lt script gt lt center gt lt br gt lt form gt Angle lt input type text name angle id angle gt lt input type button value Draw Line onclick displayLine id bi gt lt form gt lt br gt lt center gt This small application shows a compass like drawing that is going to be used to display wind direction It receives an angle in degrees as input this angle is asumed to be the current wind direction and the application draws a line to display it in a graphic sense North corresponds to zero degrees and the angles increase clockwise which means East is 90 degrees South is 180 and West is 270 lt body gt lt html gt 18 E RXTX Library Example The following file shows an example of serial communication for the WindSonic using the RXTX Java library import gnu io import java io InputStream import java io BufferedReader import java io InputStreamReader import java io QutputStream public class TalkingSerialPort params portName string This method access and returns a connection to the serial device on the address passed as ar
5. 00 COM3 9600 Output Rate 1 Hz GILLPOLAR_TWO_AXIS Figure 3 WindView displays the sensor data as received It can also display a graphic that plots both wind speed and direction as shown in Figure 4 i WRABER Data Graph Options 10 360 magnitude direction 36 2 86 m s Reset Max Min 0 00 Output Rate 1 Hz GILL_POLAR_TWO_AXIS Figure 4 WindView plots both wind speed and direction 4 For a more graphic approach WindView can also display a compass like graphic where the number corresponding to wind speed is displayed and wind direction is represented with an arrow that moves pointing on the current wind direction as shown in Figure 5 fen Anemometer 7 Windsock Data Graph Options Average Off Em Average Windspeed G nee INSTRUMENTS Gust 3s average Max Gust Min Gust 126 90 3 94 125 0 deg 2 49 m s Reset Max Min 114 0 0 00 COM3 9600 Output Rate 1 Hz GILL_POLAR_TWO_AXIS Figure 5 WindView displays a compass like graphic for wind direction and displays the number corresponding wind speed Tests were done using a floor fan to significantly increase and decrease wind speed and rotating the sensor to vary wind direction Changes in wind speed and direction were observed through the Wind View interface The WindSonic sensor operates in two modes continuous or polled In continuous mode the WindSonic takes and sends
6. 007 04 48 39 Press CTRL A Z for help on special keys CONFIGURATION MODE M4 M4 Q 000 03 M 00 2D Q 000 04 M 00 2A Q 000 04 M 00 2A Q 000 03 M 00 2D Figure 7 Screenshot of a Minicom window were change to polled mode and four measurement requests are done and answered 2 Python 2 7 2 The USPP 11 library was downloaded and installed It is a tool to communicate from a Python environment to the serial port by calling simple methods for reading and writing The USPP library has three main functions its use is explained in the Readme file shown in appendix A To read from the serial port the function in Waiting was called first it returns the number of characters left unread Then the function read n was called with n being a number less than or equal to the one returned by the in Waiting function Writing to the serial port uses the function write str with str being the command that is intended to be sent to the WindSonic In configuration mode the command string needs to end with the r character otherwise the sensor will not recognize it Some problems arose when the configuration was changed to polled mode Apparently the sensor is not reading all the characters sent but only the ones at odd positions on the command string In order to get the command D3 sent the method call write D3 r would not work If called with any other character on the even positions like write DA3B r
7. 10 Q 108 002 79 M 00 1B Q 107 002 78 M 00 15 Q 107 002 94 M 00 17 Q 107 003 23 M 00 1A Q 108 002 90 M 00 1C Q 110 003 03 M 00 1E Q 107 002 64 M 00 18 Q 112 003 63 M 00 1A Q 124 001 52 M 00 1F Q 192 000 24 M 00 12 Q 194 000 21 M 00 11 Q 198 000 12 M 00 1D Q 000 04 M 00 2A Q 320 000 06 M 00 19 Q 302 000 11 M 00 1F Figure 6 Screenshot of a Minicom window showing measurements received in continuous mode To configure the WindSonic command and return to measurement mode command Q the instructions and commands on the WindSonic user manual were strictly followed and the expected output was observed Tests were done changing configuration options and observing the expected changes in bahavior Switching from continous to polled mode and vice versa can be done as well as sending a measurement request and receiving the answer Figure 7 shows the change to polled mode with the command M4 followed by the echo made from the WindSonic Then the command was sent to activate the polled mode and command Q which is the node unique identifier was sent four times to request four measurements In polled mode the commands written and sent to the WindSonic are not displayed only the received answer root ib222m07 Te File Edit View Terminal Tabs Help Welcome to minicom 2 1 OPTIONS History Buffer F key Macros Search History Buffer 1I18n Compiled on Jan 7 2
8. Communication and Control of a Digital Wind Sensor by Victoria Pimentel and Bradford G Nickerson TR11 211 October 14 2011 Faculty of Computer Science University of New Brunswick Fredericton N B E3B 5A3 Canada Phone 506 453 4566 Fax 506 453 3566 E mail fes unb ca http www cs unb ca Contents 1 Introduction 2 2 Activities 2 3 Tests Settings 2 4 WindSonic Installation 4 5 Data Communication 5 out Java RX TX GID ALY 2 4 foc keel en heat we ch amp ble el Wee ele pla plane gh es 9 5 2 Solution to Avoid Extra Characters in Even Positions 9 6 Interface Approach 10 References 12 A USPP Readme File 13 B Example of a Kermit Input File 14 C WindSonic Command Description 15 D Interface File 16 E RXTX Library Example 19 1 Introduction This report describes the integration of a solid state wind sensor with sensor web based hardware and software The work described is part of the project entitled Web Display of Real time Environmental Sensor Data as part of the course Pasantia Larga code EP3420 from the Computing Engineering program in Universidad Simon Bolivar Caracas Venezuela 2 Activities The following activities were carried out 1 Installation of WindSonic wind sensor and first tests 2 Investigate and test data communication with WindSonic wind sensor 3 A first approach to the interface for displaying sensor data 3 Tests Settings The computers needs for this exercise
9. TML5 requires the start and end points of the line in the Canvas plane Geometry concepts where applied to the input angle so the end point could be calculated being the start point the known center of the compass as shown in Figure 8 N 0 W 270 9E 180 S Figure 8 Compass with the representation of a 130 degree wind direction Some HTML and JavaScript code were written to create a one field form where the user can enter an angle assuming it to be the current wind direction and press a button that causes the line representing that direction to be drawn in the compass appendix D shows this code The user input was used because the interface is not connected to the sensor output yet Figure 9 shows the interface with a user input of 45 degrees 10 Test Using Canvas HTML5 N 0 W270 9E 180 S Angle 45 Draw Line This small application shows a compass like drawing that is going to be used to display wind direction It receives an angle in degrees as input this angle is asumed to be the current wind direction and the application draws a line to display it in a graphic sense North corresponds to zero degrees and the angles increase clockwise which means East is 90 degrees South is 180 and West is 270 Figure 9 Screenshot of wind direction interface first draft with a 45 degree input 11 References 1 10 11 12 Anemometer contact details gill Internet accessed Septem
10. al device is established the RXTX library returns a Java InputStream for reading from the serial port and a Java OutputStream for writing into the serial port These two Java classes give flexibility for reading and writing because they can work with chars or become BufferedReader and BufferedWriter respectively to work with strings The RXTX was tested with the WindSonic in both polled and continuos mode and the expected behavior was observed The RXTX library also requires extra characters in even positions to get the WindSonic to correctly accept polled and configuration commands in polled mode just as Python and Kermit do After a command is written to the WindSonic a delay occurs before data is available to be read Our tests indicate that a sleep period of at least 250 ms is required to consistently read the data except for commands that change configuration settings of the WindSonic such as mode change that require at least 750 ms Without a sleep period blank answers are observed Using a Java library to communicate to the WindSonic throught the serial port will make easier to display sensor data in a web based interface Java applets or servlets can be used to access Java code from a web application 5 2 Solution to Avoid Extra Characters in Even Positions Gill Instruments technical support 1 was contacted in September 2011 to see if they could provide fix for missing odd characters in polled mode Murree Sims was able to provide a solu
11. are shown in Figure 1 Development computer Base station Gill WindSonic option 3 Wind sensor Wired Communication RS232c cable Figure 1 Hardware requirements for WindSonic software development In order to use the manufacturer s software e g WindView the development computer must be running Windows XP or above For the rest of the tests carried out here the development computer was running CentOS version 5 6 with Minicom text based modem control with terminal emulation installed and the Python programming language version 2 7 2 The development computer is used to receive and display data received from the WindSonic The Gill WindSonic option 3 with analog plus serial RS232 RS422 and RS485 output and serial number 08320007 is connected to the development computer through an RS232 output cable An RS232 to USB adapter is used to connect the cable to an USB serial port in the development computer The serial cable has a special connector fabricated by the manufacturer 12 A picture of the Gill WindSonic with attached RS232 serial cable is shown in Figure 2 a A picture of all the devices and instruments used for the tests described is shown in Figure 2 b Figure 2 a Gill WindSonic with the special connector fabricated by the manufacturer Fan Gill WindSonic Battery Development computer Power Special RS232 RS232 to USB USB serial supply connector cable adaptor port cable Figure 2 b Devic
12. ber 2011 http www gill co uk main contactan htm Html5 canvas tutorial accessed august 2011 Internet http www html5canvastutorials com Javascript tutorial Internet accessed August 2011 http w3schools com js default asp Jdk 7 with netbeans Internet accessed September 2011 http www oracle com technetwork java javase downloads jdk 7 netbeans download 432126 html Json Internet accessed August 2011 http www json org Node serial port github Internet accessed August 2011 https github com voodootikigod node serialport Pico github Internet accessed August 2011 https github com fergalwalsh pico Rxtx wiki Internet accessed September 2011 http rxtx qbang org wiki index php Main_Page Serializing python objects Internet accessed August 2011 http diveintopython3 org serializing html Ultrasonic wind sensor windsonic Internet accessed August 2011 http www gill co uk products anemometer windsonic html Uspp universal serial port python library ibarona Internet accessed August 2011 http sites google com site ibarona uspp Gill Instruments Limited WindSonic GPA Manual Issue 20 July 2011 http www gill co uk data manuals WindSonic GPA manual issue 20 pdf 12 A USPP Readme File This file is part of the Python library USPP This section was extracted from the Readme file and it explains how to use the library and provides an example
13. es and instruments used to test the Gill WindSonic 4 WindSonic Installation The WindSonic was connected to a 12V lead acid Discovery battery For the first test the software WindView was downloaded from the WindSonic manufacturer webpage 10 and installed in a computer runnig Windows 7 This software works for WindSonic wind sensors with serial numbers 08100001 and onwards WindView communicates with the sensor receives data and displays it WindView can show the data as received from the sensor as shown in Figure 3 For example the first line of data displayed has Q that is the instrument identifier 123 stands for the direction the wind is blowing from 002 70 stands for the current wind speed in meters per second M indicates that the unit for wind speed is meters per second 00 is the status code and 1B is the checksum Note that no date and time is available from the instrument Further details of setting display options are found in 12 TEE oaa Graph Options Q 123 002 70 M 00 4B Q 122 003 06 M 00 44 Q 123 003 20 M 00 4F 0 124 003 22 M 00 44 Q 123 003 15 M 00 49 a 124 002 93 M 00 4B Q 123 002 96 M 00 43 Q 123 003 00 M 00 4D Q 123 002 68 M 00 42 Q 122 002 82 M_ 00 47 0 120 003 10 M_ 00 4F Q 121 003 04 M_ 00 4B Q 123 003 22 M 00 4D 0 122 003 24 M 00 44 1 Q 122 002 94 M_ 00 90 E 0 123 002 58 M 00 41 130 0 3 94 123 0 deg 2 58 m s Reset Max Min 114 0 0
14. from JavaScript Testing is required 3 Use a file that saves Python output and is read by JavaScript JSON 5 can be used as a format for serializing Python objects 9 and make them accessible to other programming lenguages like JavaScript Testing is required None of these strategies were tried as a Java communication library was discovered 5 1 Java RXTX Library RXTX 8 is a Java library that provides serial and parallel communication for the Java Development Toolkit JDK To get RXTX working on CentOS Java JDK 7 with Netbeans IDE 7 0 1 4 were installed The Netbeans project has to include the jar library file under the lib project folder Also an environment variable called LD_LIBRARY_PATH has to be set from Netbeans by adding the target init macrodef java found on the build impl xml file under nbproject directory to the file buil xml and editing it by adding the following line above the customize tag lt env key LD_LIBRARY_PATH value path gt The word path should be replaced by the path to the library librxtxSerial so and librxtxParallel so files On the ib222m07 test computer the path was specified as follows lt env key LD_LIBRARY_PATH value usr java rxtx 2 1 7 bins r2 Linux i686 unknown linux gnu gt Once the installation is successfull the import to gnu io methods should be done along with the correct initializations as shown in Appendix E Once a successfull connection with the seri
15. gument static SerialPort connect String portName throws Exception CommPortIdentifier portIdentifier CommPortIdentifier getPortIdentifier portName SerialPort sp null if portIdentifier isCurrentlyOwned System out println Error Port is currently in use return sp else CommPort commPort portIdentifier open TalkingSerialPort 2000 if commPort instanceof SerialPort sp SerialPort commPort sp setSerialPortParams 9600 SerialPort DATABITS_8 SerialPort STOPBITS_1i SerialPort FLOWCONTROL_NONE else System out println Error Only serial ports are handled by this example return sp public static void main String args SerialPort sp null InputStream in null OutputStream out null String command try Call to connect method with the known WindSonic serial address sp connect dev ttyUSBO 19 if sp null in sp getInputStream out sp getOutputStream else System out println The connection was not successfull BufferedReader reader new BufferedReader new InputStreamReader in BufferedReader user new BufferedReader new InputStreamReader System in This loop performs interaction to execute on the serial device the commands written by the user and read the number of bytes selected by the user while true System out print Enter command command user readLine if command equals bye
16. measurements from one to four times a second while the polled mode sends a measurement only upon a host request The WindView software does not allow changing to polled mode so it was only tested in continuous mode 5 Data Communication Data communication between the wind sensor and the development computer ib222m07 running CentOS 5 6 was tested using three differents strategies and following the command descriptions found in the WindSonic user manual 12 for continuous polled and configuration mode Appendix C shows an extract of the WindSonic user manual that explains the available commands on polled mode and their meaning 1 Minicom With the following settings Serial Port Setup l Serial Device dev ttyUSBO Lockfile Location var lock Callin Program Callout Program E Bps Par Bits 9600 8N1 Hardware Flow Control No Software Flow Control No Qm e Modem and Dialing lA Init string Minicom provided an easy way for receiving and configuring the WindSonic If the WindSonic is turned on and connected in continuous mode which is the default mode as soon as Minicom starts the messages received are displayed in near real time as shown in Figure 6 gt root ib222m07 Te File Edit View Terminal Tabs Help Welcome to minicom 2 1 OPTIONS History Buffer F key Macros Search History Buffer I18n Compiled on Jan 7 2007 04 48 39 Press CTRL A Z for help on special keys Q 108 002 63 M 00
17. onic user manual WindSonic Unit Identifier Re Wind speed output generated Enable Polled mode none Disable Polled mode none Request WindSonic Unit Identifier Q Z as configured Enter Configuration mode CONFIGURATION MODE Where lt N gt is the unit identifier See Section 10 13 15 D Interface File The following file was created as the first approach to the sensor data interface It is written in JavaScript and HTML5 lt DOCTYPE HTML gt lt html gt lt head gt lt title gt Test HTML5 Canvas lt title gt lt center gt lt b gt Test Using HTML5 Canvas lt b gt lt center gt lt br gt lt head gt lt body gt lt center gt lt canvas id element width 800 height 610 gt This browser does not support Canvas elements lt canvas gt lt br gt lt center gt lt script type text javascript gt Calculates the second point on a line which origin is Ax Ay has a length of c and forms an angle alpha with the North function getPoint alpha Ax Ay c var alphaR alpha 0 0174532925 var a c Math sin alphaR var b c Math cos alphaR return atAx btAy Draws a line which origin is the center of the main circle has a length of the circle s radius and forms the angle inserted by the user with the north function displayLine var angle document getElementById angle value var point getPoint angle centerX centerY radius refresh elem m
18. oveTo centerX centerY elem lineTo point 0 600 point 1 elem stroke Refreshes the Canvas element for a new drawing function refresh elem clearRect 0 0 canvas width canvas height drawCircle drawLetters 16 Draws the main circle and its center function drawCircle elem elem elem elem elem elem elem elem elem elem Draws the beginPath arc centerxX centerY radius 0 2 Math PI false lineWidth 5 strokeStyle black stroke beginPath arc centerxX centerY 3 0 2 Math PI false fill lineWidth 3 stroke letters indicating the North East South and West directions with their angles function drawLetters elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem elem font 30pt Calibri textAlign center textBaseline top fillText N 400 10 textAlign center textBaseline bottom fillText S 400 610 textAlign center textBaseline middle fillText E 685 300 textAlign center textBaseline middle fillText W 90 300 font 20pt Calibri textAlign center textBaseline top fillText 0 400 45 textAlign center textBaseline bottom f111Text 180 400 565 textAlign center textBaseline
19. tion to this problem Their solution consists of sending a command character by character with an added delay between characters Tests were done using RXTX Java library adding a 20 ms delay by calling the Java Thread sleep 20 method as show in the following code char arr command toCharArray for int k 0 k lt arr length k Thread sleep 20 serialOut write arr k This solved the need for extra characters Polled and configuration commands can now be sent in polled mode without adding extra characters to the odd positions in the command string Similar results were obtained for the Python USPP library The method write ch was called once for each character of the commad string Adding delay and sending a command string character by character is not ideal Fortunately most of the commands for the WindSonic are 2 characters in length which would imply only a 40 ms delay when sending a command string 6 Interface Approach Canvas HTML5 2 and JavaScript 3 were used to create a first approach of the interface for displaying sensor data with a compass like graphic The WindSonic output for wind direction is an integer interpreted in degrees North direction corresponds to zero degrees and the angles increase clockwise which means East is 90 degrees South is 180 and West is 270 This angle will be used to obtain a line pointing in the direction of the wind On the other hand drawing a line with the Canvas element of H
20. ty write amp To request a measurement for node Q To request a measurement for node Q gt Q gt gt tty write Q To Enter Configuration Mode from Polled Mode gt Q gt gt tty write Q In Configuration Mode To check settings To check settings gt D3 Enter gt gt tty write DA3B r To change to continuous mode To change to continuous mode gt M2 Enter gt gt tty write MA2B r These methods were called along with the tty inWaiting and tty read n methods to read the answers Minicom is so far the clearer and most robust strategy for communicating with the Gill WindSonic Minicom s weakness shows when binding with a web application interface because a file is going to be needed and it may slow down the application The easiest way of working with command files is using Kermit as explained Kermit has problems when running commands from the polled mode so we might just as well use the Python library avoiding the need to use command files Now a new problem arises and it is how do we show these wind sensor observations using a web based interface Three strategies are proposed 1 Access Python code from JavaScript Pico 7 is a small web application framework that allows us to write Python modules classes and functions that can be imported and called directly from JavaScript Testing is required 2 Access the serial port from a JavaScript file Node Serial Port 6 is a library that allows access to a serial port
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