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1. C Extended ATA Send Burst J CaN Msg 6 lt tos save _ tes 6 Figure 3 2 CanalWorks in use CanalWorks can be used on WIN32 and Linux Unix The work on this application is still in progress At the moment it allows you to open several channels to the VSCP Dae mon will be discussed later and or directly to the canal interfaces You can send and receive messages choose an interface or choose which driver should be loaded set remove filter masks and allows a user to have multiple session The tool is working on both the WIN32 and the Linux platform On a top of CanalWorks there was a daemon built VSCP daemon On one side there is a canal interface for clients and on the other side there is a canal interface for drivers Programmer tells it which drivers to load at start up client can now connect to the daemon available for both Windows and Linux send a message and it will be sent to all other clients and to all devices Project offers also simple application called LoggerWnd that let you view the traffic on your net then Canalocx tool that offers ActiveX control for interfacing the daemon and many other interesting tools VSCP daemon and the applications are released un der GNU GPL license drivers classes and interfaces are released under GNU LGPL Unfortunately VSCP API is very simple and even the authors recommend to use more sphisticated API from different projects O
2. implementation of final state machine object QVcaSDOFsm class keeps the list of its SDO requests They are implemented as QVcaSDORequest objects 7 2 Specialized data structures Very important issue I had to deal with when I was reimplementing VCA library was the storage of CAN network IDs and masks as well as the storage of CANopen SDO requests Data structures that would keep the mentioned items should provide fast lookup adding and removing of an item I had considered many possible options that would satisfy these requirements e Preserve the original VCA container solution e Design specialized template structures e Use the templates from STL Standard Template Library e Use Qt generic containers 44 CHAPTER 7 QVCA VCA PORTATION TO QT Each of the considered options would bring its advantages and disadvantages Preserving the original solution would mean the use of optimized and already tested structures It would eliminate one dereference in each access and simplify many operations including type conversion hiding addition the library would remain independent from the application graphical interface This choice would not be suitable for suggested C integration so it was rejected right after I decided for the portation of VCA to Qt Design of new specialized templates would mean creating the structures that would easily use the nesting of node structures to the objects This solution would lead to the faster code
3. CAN message s can be sent only when the monitoring thread is running since the interface objects that allow the user to do so are created with the start and destroyed with the stop of monitoring thread Each message sent to the CAN bus is immediately enqueued to sent message history model used by QCANalyzer Sent Message History Tool that allows a user to resend or to keep the track of already sent messages In addition this tool provides some other functionality that will be described later in this chapter 8 2 2 1 Sending of a single CAN message Sending of a single CAN message can be done in two different ways User can send an instant CAN message from the application main window using the widgets placed at the bottom of it Another possibility is to use the application Message Sequence Tool 8 2 2 2 Sending of CAN message sequences QCANalyzer allows a user to send CAN message sequences to the CAN bus using the specialized tools e CAN message sequence tool e Sent message history tool Both tools were designed in Qt designer and both offer same set of widgets with slightly different functionality Both offer a possibility to save the messages to a file and open previously saved files After opening they can be used the very same way as it was described on previous lines 8 2 2 3 CAN message sequence tool CAN message sequence tool is a primary tool used for sending CAN message sequences It allows a user to pr
4. Qt introduces new architecture to manage the relationship between the data and the way it is presented displayed to the user This architecture is called model view programming This approach enables to keep the data independent from the graphical part which gives developers greater flexibility to customize the presentation of item and provides a standard model interface to allow a wide range of data sources to be used with existing item views classes that enable display of model s data to the user model communicates with a source of data that provides an interface for other components in the architecture view obtains model indexes references to data items from the model By supplying model indexes to the model the view can retrieve items of data from the data source delegate renders the items of data When an item is edited the delegate communicates with the model directly using the model indexes Fur 46 CHAPTER 7 QVCA VCA PORTATION TO QT ther information on model view programming can be found in online 10 For better understanding of this approach look at figure 7 6 DATA Figure 7 6 Model view programming To use model view programming technics there had to be designed a model that would store the monitored data and provide it to the view components of the application graph ical interface More important than the actual implementation of the model is what data it stores monitored CAN messages and
5. int cob unsigned long id canmsg tstamp t timestamp unsigned short length unsigned char data CAN MSG LENGTH PACKED flags flags field holds information about a message type The bit MSG marks remote 26 CHAPTER 4 LINCAN LINUX CAN DRIVER transmission request messages bit MSG EXT indicates that the message with ex tended bit 29 set ID will be send or was received The bit MSG_OVR is intended for fast indication of the reception message queue overfill cob field reserved for a holding message communication object number It could be used for serialization of received messages from more message object into one message queue in the future id CAN message ID timestamp field intended for storing of the message reception time length The number of the data bytes sent or received in the CAN message The number of data load bytes is from 0 to 8 data byte array holding message data direct communication with the driver through system calls is not encouraged because this interface is partially system dependent and cannot be ported to all environments suggested alternative is to use OCERA provided VCA library which defines the portable and clean interface to the CAN driver implementation The other issue is the addition of the support for new CAN interface boards and CAN controller chips 4 3 2 CAN Driver File Operations Following list of call operat
6. 7 4 CAN bus QObject connection new CAN mess age arrived emit CANmsgSignal E D mask message lookup broadcast ID mask list QVcaNetid QVcaNetld emit RecMsgSignal emit RecMsgSignal Figure 7 4 QVCA architecture and message distribution Original VCA architecture of CAN message distribution has not been changed Only 7 2 SPECIALIZED DATA STRUCTURES 43 the mechanism that was implemented using callback functions was replaced by the signal slot mechanism This way we get many advantages plus the source code that implements these mechanisms gets more readable QVcaNet object broadcasts all arriving messages to all present QVcaNetId objects using its particular signals QVcaNetId objects can either accept broadcasted messages or refuse them according to their set up masks 7 1 3 CANopen classes This group will be discussed very shortly since the programmed application does not provide the support for CANopen protocol yet VCA provides advanced CANopen API so I decided to reimplement at least some of its parts that will ease future CANopen support The base class of this group is QVcaCanOpenNode that represents an actual CANopen node in particular QVcaNet CAN network It contains QVcaSDOFsm object that simulates CANopen final state machine QVcaSDOFsm is just a C wrapper for the actual final state machine that is implemented in different source file and left unchanged Apart from the reference to vcasdo fsm original
7. This method of programming the scientific widgets from the scratch would require ad vanced knowledge of Qt toolkit too much code writing and additional optimization before the widgets could be used in CAN monitoring application Therefore I had decided to use the solutions offered by open source project called Qwt Although this decision will cause additional dependancy on another library I will get a benefit of already implemented and optimized objects which will lead to faster code writing 58 CHAPTER 8 QCANALYZER DESIGN AND IMPLEMENTATION ISSUES 8 4 1 Qwt library Qwt is a graphical library built upon Qt It offers a big set of classes containers and graphical widgets that can be used in the programs with technical background Besides a simple 2D plotting widgets it offers scales sliders compasses wheels and many other scientific widgets to control or display the values of type double Although it was not inte grated with the whole framework Qt designer provides a support for basic Qwt graphical widgets Library is distributed under LGPL license and can be used in all environments where Qt can be used Only inconvenience that it brings is that Qwt does not provide binary packages Instead all source files have to be downloaded and compiled the way any other Qt based program is compiled More information on Qwt can be found at project s http pages 11 8 4 2 Plotting of monitored data Data transferred by CAN messages in m
8. EJ OCERA project development web pages ttps sourceforge net projects ocera El Gtk project documentation ttp gtk org ph Qt framework web pages http trolltech com products qt Java SWING tutorial web pages ttp java sun com docs books tutorial uiswing Qt framework online documentation ttp doc trolltech com 4 3 7 Qwt Project Online Documentation ttp qwt sourceforge net 2 I ev 74 BIBLIOGRAPHY Attachement A List of abbreviations ISO The International Organization for Standardization IEEE The Institute of Electrical and Electronics Engineers IETF The Internet Engineering Task Force CAN Controller Area Network GUI Graphical User Interface ISOOSI ISO Open Systems Interconnection Model EDS Electronic Data Sheet PDO SDO Process Service Data Object NMT Network Management Technology SYNC Synchronization Object OCERA Open Components for Embedded Real time Applications API Application Programming Interface GPL General Public License LGPL Lesser General Public License ANSI C American National Standards Institute standard for the C programming lan guage II ATTACHEMENT A LIST OF ABBREVIATIONS Application Programming Interface VSCP Very Simple Control Protocol GAVL AVL Generic Generalized Adelson Velski Landis trees KDE K Desktop Environment GNOME Desktop environment for computers running Unix based operating systems GNU
9. Computer operating system composed entirely of free software JFC Java Foundation Classes STL Standard Template Library TFT Traffic Filtering Tool
10. OPEN SOURCE PROJECTS 17 e CANFestival GUI acts as a CAN sniffer receiving of CAN Messages is done in separate thread e Values which should be sent over the CAN CANopen network can be typed in as hex decimal or binary values Each of them can be converted to the other formats Objdictedit TestMaster TestMaster 0x0001 OxOFFF Data Type Definitions 0x1000 0x1029 Communication Parameters 0x1200 0x12FF SDO Parameters 0x1400 0x15FF Receive PDO Parameters 0x1600 0x17FF Receive PDO Mapping Device Type O Have Callbacks Error Register subindex access SYNC COB ID Communication Cycle Period Consumer Heartbeat Time Number of Entries 4 Read Only Vendor ID INTEGER32 0 00000000 Read Only Product Code INTEGER32 0x00000000 Read Only Revision Number INTEGER32 0x00000000 Read Only Serial Number INTEGER32 0x00000000 Read Only Figure 3 1 CANfestivalGUI in use CanFestival runtime library is released under LGPL license thus it can be linked with any code proprietary or not Bindings are very simple and can be theoretically adapted to any target or CAN interface CANFestival necessary requirement is the only PC CAN Board supported AdLink PCI 7841 Card In order to be able to use the CANFestival GUI you need at least the following things e Qt 2 x installed on your computer e AdLink PCI 7841 Board is recommended but if you do not own such a card you can still use this program in
11. application is the class that implements the ap plication main window It is called MainWindow MW and consists of several other objects Instance of MW is the parent object of all objects in the whole application parent children hierarchy It has to be underlined that the terms application main win dow and Main Window have different meanings in this text application main window represents graphical object that is displayed to the user when the application is started while MainWindow represents the class that defines and implements application main window functionality Design and implementation of MW as well as all components it consists of will be discussed on following lines in more detail with regard to particular application functionality requirements 8 2 1 CAN network traffic display Monitored CAN message traffic is displayed in QCANalyzer main window It was de signed in Qt designer tool for designing and building GUIs from Qt components Output of Qt designer is a customized XML file called user interface form With Qt s integrated qmake tool the code for user interface created with Qt Designer is generated automat ically when the rest of the application is built Forms can be included and used directly from the application or they can be used to extend standard or user customized wid gets MW inherits Qt designer generated form and implements the functionality of each graphical object that it contains This way the implementat
12. display 13 14 CHAPTER 3 RELATED PROJECTS of traffic sending of predefined message sequences etc What distinguishes this tool from other commercial programs are several special func tions that it provides From many of them the most interesting is programmability with CAPL Communication Access Programming Language By programmability I mean adjusting of user needs by inserting special graphical blocks at any point of data flow plan so the user can program their function with the use of C like language CAPL for which it has an interactive development environment Tool supports all bus interfaces of fered by Vector Complete list of supported HW can be found on company s 2 CANalyzer system requirements e Processor Pentium 4 2 6 GHz Pentium III 1GHz e Memory RAM 1 GB 512 MB e Hard disc space 200 600 MB depending on the chosen option e Operating system Windows Vista XP SP2 2000 SP4 Vista for CAN and LIN only XP and Vista only 32 bit 3 1 2 PCAN Tools PCAN is a a package of software tools developed by the Peak company It comes on dedicated CDs for free with the purchased HW modules It covers the wide range of tools From simple CAN monitoring ones like PCAN View to more advanced tools like PCAN Explorer PCAN Explorer provides all necessary functionality needed for ad vanced monitoring and analysis of CAN based systems advanced logging mechanism graphic views of monitored messages and data support of
13. how In addition possible multithreaded archi tecture of developed application had to be taken in mind To deal with the minimizing of copying of data maximizing of resource usage and multithreading there was designed a new object that fulfilled all mentioned requirements Qt offers the resources to enable creating such an object Implicitly Shared Classes An implicitly shared class consists of a pointer to a shared data block that contains a reference count and the data When a shared object is created it sets its reference count to 1 The reference count is incremented whenever a new object references the shared data and decremented when the object dereferences the shared data The shared data is deleted when the reference count becomes zero The benefit of sharing is that a program does not need to duplicate data unnecessarily which results in lower memory use and less copying of data Implicitly shared classes can be safely copied across threads like any other value classes They are fully reentrant which is implemented using atomic reference counting operations Atomic reference counting is very fast much faster than using a mutex Even in multithreaded applications you can safely use them as if they were plain 7 4 CONCLUSION 47 non shared reentrant classes Further information can be found Qt implicitly shared classes documentation 10 Apart from implementing CAN message as implicitly shared object I decided to use th
14. inspiration for my own application Open source projects offer also some advanced applications but they have several issues CANFestivalGUI offers a smart CANopen tool but on the other hand this tool is programmed using Qt 2 x which is a very old version of this library and not further supported by the vendors of Qt So the possibility to extend this application was refused by this fact VSCP project offers the CanalWorks application but it uses only a very simplified API Even by the authors of the VSCP recommend to use more advanced API like the one offered by the OCERA project in order to create a more advanced tool I had decided to use in my work some of the components offered by the OCERA project due to the following reasons e it is testted currently being used by some companies in their industrial applications e it is released under GPL license e it offers a LinCAN driver to enable communication with several HW interfaces and canmond daemon for the remote monitoring e it offers a sophisticated VCA virtual CAN api system independent library e some of the project contributors work at my university so there is an easy way to contact them and consult any problem LinCAN driver and the Virtual CAN API library will be shortly discussed in next chap ter 22 CHAPTER 3 RELATED PROJECTS Chapter 4 LinCAN Linux CAN driver 4 1 Overview LinCAN is a Linux kernel loadable module that implements a CAN driver capable of
15. of warnings about bus overload Overload Notification 2 31 Medium Acces Control If a bus is in a Bus Free state any of the connected nodes can start a transmission First one that starts it gets the bus for itself and the rest of connected nodes have to wait until it is finished transmitting a message Then they can start transmitting if they get the bus for themselves The only exception is the error frame transmission that can be transmitted by any node if it detects an error in actual broadcasting message If several nodes start transmission at once then the access to the bus is gained by the node that transmits a message with the higher priority lower identifier Every transceiver compares the actual transmitted bit value with the bit value on the bus and if it finds out that they differ the only possibility is when it is transmitting a recessive bit and there is a dominant bit on the bus it immediately interrupts the transmission Described real time concurrent transmission by several nodes is shown at figure 2 3 2 3 DATA LINK LAYER 9 Figure 2 3 CAN data transmition This guarantees that a message with a higher priority will be sent preferably and that it does not get corrupted That could result in retransmitting of the message and an unnecessary time delay needed for transferring of the message The node that didn t get the access to the bus must wait until the bus will be back in the Bus Free state Then it can try to
16. there is some traffic on monitored CAN network it is immediately dis played in application main window message table view if it passes set up traffic filters Statistics table view right under the message log shows the number of received messages of particular message ID Filter displayed Figure 9 3 QCANalyzer in use Screenshot of running application is shown at figure 0 3 CAN message fields shown in particular column of the application main window traffic view are displayed in hex adecimal form Displayed traffic view can be cleared using the CLEAR LOG button placed above the main traffic table view After this action no messages will be displayed in a traffic view Message ID statistics remain unchanged If a user decides to clear both views traffic and statistics views he must click the CLEAR ALL button that is next to the previously mentioned button User can even hide monitored statics unchecking by defeault checked VIEW STATISTICS checkbox User comments can be added to every monitored message and to every message ID statistics User can filter the displayed messages by typing the message ID or message flags filtering condition to prepared fil tering line edits placed at the top of main window While the application is connected to the driver user can send single message using the main window widgets placed at 9 2 BASIC FUNCTIONALITY 65 the bottom of traffic tab pag
17. toolkit couple of years ago when I was trying to develop CAN monitoring application warned me before using it again Development of CAN monitoring tool went quite slowly mainly because of the documentation resources GTK web pages offer short tutorial and API reference but for a person who has never used it before it is very difficult Java is a cross platform object oriented programming language It has a lot of ad vantages advanced documentation resources portability to different operating systems and many other Even the OCERA project offers simple monitoring application that is written in Java SWING I could easily continue in its developement but sevral reasons made me reject this option I will mention the one that I found the most important portabiliy of Java even the execution of any Java program is strongly dependant on its version although its developers would disagree According to the problems that would come out if GTK or Java SWING was used for development of CAN monitoring application I turned my attention to Qt First I had to accept some handicaps that this solution would bring Programming in Qt will cause a little slow down of the application comparing to the GTK because of the over head that comes with the object oriented programming but it would still be faster than any Java based program Plus connecting a graphical interface to already prepared VCA API would require some additional changes that would
18. whole application It is this tool s model slot that performs first processing of received CAN messages CAN message received emit acceptedCANmsg Figure 8 4 QCANalyzer traffic filtering The pinciple of CAN traffic filtering implemented in TFT can be understood from the figure 8 4 When a new message is received by OVCA interface object it is emitted by the signal that is connected to TFT model slot ID of received message is checked against all set up masks in TFT model If it passes any of the accept mask compare it is emitted by another signal that is connected to MW CAN message model slot T hen it is enqueued to its model and displayed to user If ID of new arriving message doesn t get through any of the accept masks or if it passes any of the reject masks it is immediately rejected and not displayed in the main window Memory allocated for the message is released automatically since the reference for the implicitly shared object in this case CAN message will no more exist 8 4 PLOT DISPLAY OF MONITORED DATA 57 8 3 2 View filtering View filtering covers displaying only those items in the view that match some user fil tering conditions or expressions View filtering is implemented using specialized model offered by Qt QSortFilterProxyModel It provides the support for sorting and filtering of data passed between another model and a view QSortFilterProxy model is applied on already existing model which is refered to
19. working with multiple cards even with different chips and IO methods Each communi cation object can be accessed from multiple applications concurrently Most important feature is that the driver supports multiple open of one communication object from more Linux and even RT Linux Real Time applications and threads The usage of the driver is tightly coupled to the virtual CAN API interface component which hides driver low level interface to the application programmers LinCAN supports RT Linux 2 2 2 4 and 2 6 with fully implemented select poll fasync O NONBLOCK and 0 SYNC seman tics and multithreaded read write capabilities It works with the common Intel 182527 Philips 82c200 and Philips SJA1000 in standard and PeliCAN mode CAN controllers actual version has been tested at CTU by more OCERA developers by Unicontrols and by BFAD GmbH which use pre OCERA and current version of the driver in their products Each chip CAN interface is represented to the applications as one or more CAN message objects accessible as character devices The application can open the character device and use read write system calls for CAN messages transmission or reception through the connected message object parameters of the message object can be modified by the IOCTL system call The closing of the character device releases resources allocated by the application The intelligent CAN CANopen cards should be supported by the near future One o
20. writing but slower optimization Using the templates from STL would lead to the previous problem Plus STL does not contain environment good enough for our needs so there would still be need for creating of new templates Using the Qt generic containers would mean a dependance on graphical library but I had accepted this constraint when I decided for the portation VCA to Qt 7 2 1 Qt generic containers Qt framework provides a set of template based container classes They can be used to store items of a specified type Container classes are designed to be lighter safer and easier to use than the STL containers They are implicitly shared method that maximizes resource usage and minimizes copying of data fully reentrant and they are optimized for speed low memory consumption and minimal inline code expansion resulting in smaller executables In addition they are thread safe in situations where they are used as read only containers by all threads used to access them Index lookup Insertion Prepending OList lt T gt O 1 O n Amort O 1 Amort O 1 OVector lt T gt O 1 O n O n Amort O 1 Keylokup Insertion QMap lt Key gt O log m O logm O logz O logn OHash lt Key gt Amort 1 O n Amort O 1 O n Figure 7 5 Algorithmic complexity of Qt generic container classes From all the container classes offered by Qt I was considering four of them as a substitution of origin
21. 6 24 DT 25 MEME 25 26 jo dol 27 5 VCA Virtual CAN 29 5 1 VCA Base CAN Protocol Supporti EC 30 5 2 VGA CANopen Protocol 5 32 bo Utility Functiong aeu aa 32 6 Graphical library 33 33 34 34 34 37 t 37 7 11 CAN interface classed oe 39 7 1 1 1 QVcaBuslfcAbstrac 39 71 1 2 QVcaBuslfcLinCAN 40 7 1 1 3 OVeaBbuslteSocketPickld 2222222 org 41 sis 42 ee oan 4s 43 PNE 43 ee 555555245266 45 CA Conclusi n 50 2 2409 Ro do m Z 47 49 Lecce ue neue RN 49 MT 51 nen 51 8 2 2 Sending of CAN message 53 8 2 2 1 Sending of a sine 54 8 22 2 Sending of CAN message sequenced 2 2 2 2 54 MEE 54 ee be a sw 55 ved CAN messaged 55 Le pe bebe h b eee ees 56 P 57 2 57 T 58 e a 58 59 61 yze 61 62 v 62 92 3 Saving and Opening monitored traffic filed 65 9 204 OCANalvzer specialized toold 0008 66 92 4 1 Message sequence 001 66 9 2 4 2 Sent message history too 345022250222 475 67 9 2 4 3 filtering tool 222 on 68 925 QUAN VE aeos Ede m Pe da 69 10 Conclusio 71 Bibliography 73 List
22. CANopen etc PCAN Light tool enables a selection of different drivers for Windows and Linux operating system PCAN development tool allows a programmer to develop its own application using API libraries provided in form of precompiled libraries Unfortunately these APIs offer only a small range of functions open close write read status setfilter resetfilter resetclient etc On the other hand they are available for different programming languages C C Delphi Borland Builder VB NET and VB header files and come with the HTML documentation as each tool in this package Peak offers a freely downloadable driver for Linux operating systems but it supports only a small group of all HW compoments developed by the Peak company The whole list can be found on company s web pages 3 3 2 OPEN SOURCE PROJECTS 15 PCAN System requirements e Windows 2000 XP Vista e at least 256 MB RAM 700 MHz CPU e Hard disc space 100 500MB depending on the chosen options 3 1 3 PORT Port is another company offering CAN monitorubg software tools Apart from develop ing of their own CAN HW modules they offer a simple CANopen device monitor tool programmed in Tcl Tk Tcl Tk is a GTK library binding for Tcl scripting language This tool provides a basic CANopen features editing of EDS SDO PDO transfers NMT atc The usage of the CANopen Device Monitor requires a CAN interface currently available interfeces are USB ISA PCI paral
23. CERA or CANpie API 20 CHAPTER 3 RELATED PROJECTS 3 2 3 OCERA that stands for Open Components for Embedded Real time Applications is an European project based on Open Source which provides an integrated environment for embedded real time applications OCERA combines the use of two kernels Linux and RTLinux GPL to provide support for critical tasks RTLinux GPL executive and soft real time applications Several components for both environments have been developed to bring an innovative development and deployment platform to the embedded system developer The OCERA project offers LinCAN LinuxCAN driver that supports many hardware interfaces Appart from the driver it offers a simple monitoring tool pro grammed in Java that provides some basic monitoring features like sending of messages to the bus receiving loading and editiing of EDS files and some other additional func tionatilities un CANopen monitor Beta 0 9 x File Tools gt x Quit CAN 61 Show rough messages D hex Mask hex Clear log e id 5 flags 0 length 8 data 01 50 03 04 05 06 07 08 RECEIVE 65 3 CAN message id 5 flags 0 length 8 data 02 50 03 04 05 06 07 8 RECEIVE 65 4 CAN message id 5 flags 0 length 8 data 03 50 04 05 06 07 O8 RECEIVE 655 CAN message id 5 flags 0 length 8 data 04 50 03 04 05 06 07 O8 RECEIVE 656 CAN message id 5 flags 0 length 8 data 05 50 03 04 05 06 07 08 RECE
24. CZECH TECHNICAL UNIVERSITY IN PRAGUE FACULTY OF ELECTRICAL ENGINEERING DIPLOMA THESES CAN bus communication protocol support and monitoring Prague 2008 Milos Gajdos Acknowledgements I would like to thank the chief of my diploma thesis Ing Pavel P a for his patience help and suggestions which were very much appreciated My special thanks go to Ing Franti ek Vacek who helped me with the practical aspects of this theses and without whom this theses would not reach the quality as it has now Many thanks go also to Bc Luk s Stan k for several suggestions and remarks on developed project Last but not least I would like to thank all my close friends and family for their support Abstrakt T to pr ca sa zaober monitorovan m syst mov zalo en ch na komunika nom pro tokole CAN Controller Area Network Hlavn m cie om pr ce je port cia monitoringu a posielanie testovac ch spr v v prostred jazyka C s vyu it m grafickej kni nice Qt Teo retick as pr ce popisuje z kladn princ py protokolu CAN a zaober sa n vrhom dis trib cie a filtr cie monitorovan ch spr v do jednotliv ch komponent grafickej aplik cie s vyu it m pripojenia tejto aplik cie k ovl da u CAN Praktick as popisuje n vrh a im plement ciu grafickej aplik cie nazvanej OCANalyzer ktor by mala podporova anal zu vy ch vrstiev komunik cie pre ahk nasadenie v automobilovom priemysle rovnako ako interp
25. IVE 65 7 CAN message id 5 flags 0 length 8 data 06 50 03 04 05 06 07 08 RECEIVE 658 CAN message id 5 flags 0 length 8 data 07 50 03 04 05 06 07 08 RECEIVE 65 9 CAN message id 5 flags 0 length 8 data 08 50 03 04 05 06 OF O8 RECEIVE 660 CAN message id 5 flags 0 length 8 data 09 50 03 04 05 06 07 O8 ID byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7 RTR OVR HL j IL JL IL Jl j Ber Ltocat Socket addr localhost 127 0 0 1 port 10001 l0calport 601 76 1 1 Send Figure 3 3 Canmonitor in use Canmonitor shown at figure B 3 is a simple TCP IP client that connects to a can monitor daemon called canmond which enables sending and receiving of CAN messages via TCP IP protocol Its greatest advantage is that it is programmed in Java multiplatform portability but it lacks a lot of useful features in a view of user needs The greatest advantage of the OCERA project is its high level virtual CAN API provided for system programmers to enable them communication with the LinCAN driver 3 2 OPEN SOURCE PROJECTS 21 3 2 4 Conclusion From the researched projects I deduced several conclusions Commercial projects like the Vector CANalyzer or the Peak PCAN Explorer are very advanced tools and are still being developed by many programmers In this work I can only try to come close to these projects and at least get some
26. QObject It means that they inherit QObject class which is the base class of all Qt classes QObject is the heart of the whole Qt object model Very advanced and a probably the most powerful QObject feature is a mechanism for the object communication called signals and slots Figure 7 1 Signals and slots mechanism The signal slot mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks Signal is emitted when a partic ular event occurs Qt s objects have a lot of predefined signals but a programmer can simply subclass any QObject and add his own signals to it Slot is a function that is called in response to the particular signal There is a lot of predefined slots for particular Qt objects but a programmer can create its own ones and connect them to the particular signals Several slots can be connected to several signals as far as the signal signature matches the signature of the receiving slot In fact a slot may have a shorter signature than the signal it receives because it can ignore extra arguments For better understand ing of signal slot mechanism look at figure I 7 1 C INTEGRATION OF CHOSEN COMPONENTS 39 The signal slot mechanism is in comparison to the callback mechanism used in VCA type and thread safe When using the callback functions one can never be sure that the processing function will call the callback function with the correct argument
27. ach other It is the time that it takes to get from one node to the furthest one considering the delay caused by transmitting and receiving synchronization and the signal that returns back from the second one to the first one Only then can the first node distinguish either its own signal level is the actual level on the bus or it has been replaced by the dominant level by another node This fact is important for the bus arbitration In order to achieve the highest possible bit rate at a given length a high signal speed is required Maximum bus line length for the transmission rate of 1Mbit s is 40 meters 8 CHAPTER 2 CONTROLLER AREA NETWORK CAN The standard doesn t specify the bus line length for other transmission rates Other lengths for other transmission rates than 1Mbit s depends on many parameters eg type of cable etc However it can be proven that for lower transmission rates the maximum bus line lengths will be bigger 2 3 Data Link Layer The data link layer consists out of two sublayers MAC Medium Access Control and LLC Logical Link Contol First of them takes care of medium acces provides bit coding bit stuffing and destuff ing controls the access of all connected nodes to the physical medium connsidering the message priority detection of errors and their reporting and finally acknowledging of correctly received messages The second one takes care of message filtering Acceptance Filtering and reporting
28. al VCA constructs As for the GAVL AVL trees I was considering 7 3 EXTENSIONS AND ENHANCEMENTS 45 QHash or QMap and for the GSA lists QVector or QList At last I had decided to use QMaps and QLists QHash in comparison to QMap offers faster lookups since it stores its data in an arbitrary order but QMap stores the data in key order what can be sometimes very useful QVector stores an array of values at adjacent positions in memory Inserting at the front or in the middle of a vector can be quite slow because it can lead to a large number of items having to be moved by one position in memory That is why I decided to use QList Summarizing table 7 5 shows the algorithmic complexity of Qt generic container classes It can be assumed that chosen solution will sufficently fulfil all requirements for the new storage structures and won t cause any noticeable inconvenience 71 3 Extensions and enhancements Apart from the changes that enabled portation of VCA to QVCA I had suggested and implemented some useful features that simplify connecting of QVCA to the application graphical objects These features represent an imaginary bridge between the graphical and non graphical part of the application I have decided to keep them as a part of QVCA independently of the graphical part as it is required when one wants to use Qt s model view programming technics that simplify the presenting of the data to he user 7 3 1 Qt model view programming
29. al practice when a new software is going to be developped either by company or by any programmer This research gave me a picture about what commercial and open source software dealing with CAN monitoring looks like since the graphical user interface is very important part of this work and what functionality it offers to its users I had put the emphasis on portability to different operation systems and also on supported hardware When researching the open source projects I considered also a possibility of their further extension while researching of the commercial projects was based on strictly practical reasons List of researched projects with additional discussion can be found in the third chapter of this work CHAPTER 1 INTRODUCTION Chapter 2 Controller Area Network CAN 2 1 Overview Before I start to talk about actual the aspects of this diploma theses I will shortly present at least some of the basic principles of CAN that are necessary for understanding of the whole concept of this work CAN is a serial bus system originally developed by the BOSCH company for automo tive applications in the early 1980 s It is being used in a large and still growing extent especially in automotive industry for which it was designed but currently also in chem ical industry and in many other branches of automation CAN is currently supported by many leading manufacturers of integration circuits It became a favourite alternative when designin
30. are some precompilation prerequisities that need to be satisfied in order to compile the program e Qt toolkit must be installed at least version 4 3 e Qwt library must be downloaded and compiled from its source codes On some Linux OS distributions debian ubuntu Qt and Qwt is distributed in binary packages so there is no need for their additional compilation Qt and Qwt documentation describes how to compile these two libraries using Qt tools on different OS You can find more information about Qt application deployment in dedicated manual 10 We assume that user has installed and deployed Qt and Qwt libraries as it is described in their documentation Now the source files of the QCANalyzer application distributed in one tar file have to be downloaded and compiled In order to compile the application read the following installation steps 1 Generate a Makefile using qmake utility this way qmake o Makefile src pro 2 Run make utility Compilation should pass without any warnings Built application binary file called qc analyzer can be found in bin project directory Now the user can copy the application 61 62 CHAPTER 9 QCANALYZER USER MANUAL binary to his directory or it can be executed from the directory where it was built 9 2 Basic functionality QCANalyzer can be started either by double click on the program executable or from the command line When a user starts the application from the command line he can specif
31. as a source model QSortFilterProxyModel works as a wrapper for the original source model It transforms maps source model in dexes it supplies to new indexes for different views to use This enables source model to be reorganized as far as the views are concerned without any transformation of model s data Plus the data stored in the original model is not duplicated Actual view filter is imeplemented using QRegExp object It can be used as a wildcard pattern a regular expression or a fixed string Whenever it changes a signal that notifies the QSortFil terProxyModel model is emitted QRegExp is applied to the filter role display role by default of each item Items that don t match filtering expression are hidden in the view View filtering is implemented in every QCANalyzer widget that provides a table view main window message log message sequence and history tools and message filtering tool User can specify filtering expression by typing it into tool s line edits placed at the top of the view which reflects applied changes immediately It had to be reminded again that this mechanism filters only already displayed data it won t filter message traffic or any other data Data that does not match the expression specified byt the user remains stored in original model during the filtering action 8 4 Plot display of monitored data Qt offers a large set of objects that allows a user to create sophisticated scientific widgets
32. be found on web pages maintained by the group of CAN manufacturers 1 12 CHAPTER 2 CONTROLLER AREA NETWORK CAN Chapter 3 Related Projects This chapter lists and shortly presents the most interesting projects dealing with the CAN monitoring subject that I have found on the internet These projects can be divided by many criterias I have chosen one of the most important when deciding to create or bring a new application on a software market economical criteria By that we can divide these projects to Commercial protected by copy rights and Open Source source codes are freely downloadable and distributable It depends on your actual needs and economical status which one you decide to choose I have chosen three projects I considered the best from each group 3 1 Commercial projects Commercial software offers a lot of advantages from which most important are main tanance and support of the company that develops and sells it On the other hand it has many disadvantages unavailability of application source codes expensiveness undesired functionalities and so on 3 1 1 CANalyzer It is developed by the Vector company It provides advanced software tools not only for monitoring of CAN based systems CANalyzer offers a graphic block diagram interface from which CAN based system is controlled or monitored The basic functions offer multiple usage options monitoring and listing of a bus traffic graphical or textual
33. cify any of mentioned fields in hexadecimal mode he has to put 0x prefix before the actual number Data field is automatically converted to hex form User can decide either to send all messages or only the ones selected by the mouse Messages are being sent in the order they are displayed in tools s view as it is shown at figure 9 5 or in a way they were selected by the mouse 9 2 BASIC FUNCTIONALITY 67 Send Message Seguence Tool CAN message seguence name Filter displayed messages some important message 23460 config message Remove actions Send actions Remove actions Figure 9 5 Message sequence tool in use User can remove alreadey prepared or sent messages He can remove either all or only the selected ones Sending or removing of selected messages can be also done by clicking the item in the context menu called by the mouse right button click or clicking coreesponding item in tool s Message menu bar Tool also offers a possibility to save prepared messages either in binary or text form and open already saved messages Several can message tools can be opened from the application main window Tool also provides the option of dropping the messages from the mainwindow traffic view from the log file opened in it or even from sent message history tool that will be describe in next section User can specify the name of prepared sequence in a SequenceName line edit placed at
34. computation is running in the background Moreover multithreading increases the program performance and lowers memory consumption Qt provides quite an advanced multithreading support Apart from platform independent classes it offers a thread safe way of communication across the threads the signal slot mechanism QObject connection 9999 onnect QVcaBuslIfc CANmsgSignal GUTOhject receiveSlot connect QVcaBuslfc CANmsgSignal 4 QVcaNet receiveSlot CAN bus Figure 8 1 QCANalyzer architecture In a following text non graphical thread that takes care of actual CAN traffic mon itoring will be refered to as monitoring thread and the graphical thread in which the 8 2 IMPLEMENTATION 51 graphical part of the application is running and which allows a user to watch the moni tored traffic main application thread Monitoring thread is created and then immediately started from the main application thread using particular QCANalyzer widget Thread creates QVCA network as well as QVCA interface objects that perform actual CAN bus monitoring and CAN message distribution to different parts of the application in a way that was described in previous chapter QVCA interface object signals that distribute received CAN messages are caught by corresponding slots in main application thread which performs their further processing Described mechanism is shown at figure 5 1 8 2 Implementation Base class of the whole QCANalyzer
35. creating graphical user interfaces It offers a large of different widgets It is a free software released under LGPL license and a part of the GNU Project GTK has been designed to support not only C C programming language It also provides the support for the scripting languages such as Perl Python and many others the whole list of supported bindings can be found on GTK web pages 7 Today is used by a large number of applications From all of them Wireshark or the GNU project s GNOME desktop environment are the most famous 33 34 CHAPTER 6 GRAPHICAL LIBRARY 6 2 Qt Qt offers the whole framework for high performance cross platform not only graphical application development It is produced by the Trolltech company It includes e intuitive easy to use class library e Integrated development tools qmake Qt Linguist Qt Designer Qt Assistant e Support for C and Java development Qt uses C with several non standard extensions It can be used in other programming languages too Current supported bindings exist for Python PyQt Ruby RubyQt PHP PHP Qt Pascal C Perl Java and Ada Qt based programs can be run on all platforms Win32 Linux OS MAC OS X Appart from the commercial edition Trolltech offers also an Open Source freely downloadable edition The use of Qt in application de velopment is increasing every year and the community of Qt developers is hugely growing From many projects
36. developped in Qt it is enough to mention KDE desktop environm ment for Linux and Unix workstations Mathematica Opera web browser Google Earth or Skype Further information about Qt development framework can be found on Qt web 8 6 3 Java SWING Swing is widget toolkit for Java It is a part of SUN Microsystem Java Foundation Classes JFC an API providing a graphical user interface for Java based programs As Java it is a cross platform toolkit that guarantees uniform look and behaviour on all platforms Further information about SWIN can befound on projects web pages 9 6 4 Conclusion GTK basic API is is based on C programming language Since the is also programmed in C using GTK for GUI development of this application would speed up the whole development process Structures and mechanisms provided by VCA could 6 4 CONCLUSION 35 easily be connected to GTK graphical objects without any major change of their imple mentation Programming in C offers also a speed advantage of a programmed application and eventually better portability On the other hand writing a graphical application is a process completely different from developing of a typical console program or library It would require to design a lot of graphical object which would be easier implemented using an object oriented approach Another big disadvantage of developing in GTK4 is its poor documentation My experience with the GTK
37. e He can specify the message ID either in decimal or in hexadecimal form When typing the hexadecimal number user must add 0x prefix before the actual hex value so the application could recognize value form Message is sent using the SEND button Monitoring can be stopped by clicking the Detach in terface toolbar button or from the Tools menu or using the keyboard shortcut F6 This button is by default disabled when the monitoring is not in progress Clicking it will exit the monitoring thread so no other message will be displayed in message log 9 2 3 Saving and Opening monitored traffic files When the monitoring is stopped user can save the displayed messages to the file either to text or to binary file Saved text files have tlog suffix added while the binary files have blog so they can be recognized when a user wants to open any of the log files in some text or hexa editor User can save the message log in a similar way as previous actions were described clicking the Save tool bar button using the File menu or using the usual save keyboard shortcut Ctrl4 S Saving the log files is disabled when the monitoring of the CAN bus is in progress Figure 9 4 Save message log dialog Apart from saving the monitored log to the file application provides a possibility to open already saved log files Open files is enabled through the similar dialog window as the save dialog one shown at figure 9 4 It can be cal
38. e t has common specification language MDF that describes a module in an uniform way that can be used by set up software 3 2 2 1 CANAL CAN Abstraction Layer CANAL is the lower layer for the CAN based nodes It is built as two separate solutions just to make the CANAL useful also for other CAN tasks It defines a message format and some basic function calls On top of this some CAN drivers have been built The can232 driver for the Lawicel adapter is a typical example but there are being developed other for IXXAT Zanthic Technologies Inc Ferraris Elettronica Vector OMK OCERA project and all the others The whole list can be found on the project 4 Application rogrammer can use one programming interface to all of them Thus one can build the application that works with the different types of hardware A typical example of this kind of application is the Canal diagnostic tool CanalWorks that can work directly with any available device Screenshot of the application is shown at figure 9 2 3 2 OPEN SOURCE PROJECTS 19 Y CanalWorks x Canal InterFace Window Hep OBEH BA 82 daemon interface CANAL Session 1 00000000 00000000 00000078 7 01 02030405 06 07 Tx 2004 12 06 10 51 58 00000000 00000000 00000078 01 02 03 04 05 06 07 Rx 2004 12 06 10 52 18 00000000 66 RX 2004 12 06 10 52 20 00000000 66 Al E gt Select View Id Data can sos m 6 OT S af Sf ef I
39. e very same way for SDO requests implementation too Although SDO request objects will not be used in this work it will ease further extension of the application to support CANopen protocol QVCA CAN message model was designed as an abstract class with one virtual method CAN message receiving slot This was done to enable the use of this model for different kinds of message processing tasks in different graphical widgets that will eventually use it 7 4 Conclusion Portation from to QVCA turned out to be the right solution after all It brought many useful features Signal slot mechanism enabled simple communication between the QVCA objects Model view programming separated graphical and non graphical part of the application and concurrently created a bridge between them Qt template structures replaced original VCA constructs without any noticeable inconvenience and made the source code more readeble At last implicit sharing improved application memory and resource usage and simplified possible multitheading issues 48 CHAPTER 7 VCA PORTATION TO QT Chapter 8 QCANalyzer design and implementation issues QCANalyzer is a graphical application that allows a user to interact with the CAN bus It is a simple CAN monitoring tool that enables to analyze monitored CAN traffic either from a live CAN network or from a previously saved traffic files Instead of offering typed commands it gives a user possibility to use
40. ed physical media to implement CAN based networks is a differentially driven pair of wires for vehicle body electronics single wire bus lines are also used according to ISO 11898 standard This standard defines electrical behaviour of transmitter and receiver as well as timing principles bit encoding and decoding synchronization and bit timing The bus consists of two line wires marked as CAN H and CAN_L where the dominant or the recessive level is determined by differential voltage of these two wires The bus is adjusted on both ends by using terminating resistors to eliminate bounces on a power line Fundamental structure of a CAN network according to ISO 11898 norm is shown at figure 2 2 Node Node 1 Terminating e CAN 1 Terminating resistor resistor 120 2 CAN L 1202 Bus length Figure 2 2 CAN network structure according to ISO 11898 There is limit for number of the nodes connected to the bus caused by CAN pro tocol principles Only maximal number of different message types is limited by size of the message ID fiels But with regard to bus and to ensure the correct static and dy namic parameters of the bus the standard recommends maximum amount of 30 nodes Depending on a number of connected nodes that causes a data propagation delay maxi mum possible bus length at a specific data rate is determined The signal propagation is determined by the two nodes within the network that are furthest apart from e
41. en there is some data available for reading on device file descriptor used for monitoring QSocketNotifier emits a signal 7 1 C INTEGRATION OF CHOSEN VCA COMPONENTS 41 which is then caught by VcaBuslfcLinCAN slot connected to it In this slot new CAN message is received using the read function called on the file decriptor to which QSocketNotifier is bound and then immediately emitted with QVcaBusIfcLinCAN CAN message dsitribution signal If a programmer decides to do some other processing with the received message he can just simply connect some other QObject s slot s to this signal Sending of CAN message is performed the very same way that is implemented in VCA using the write function called on particular CAN device file descriptor 7 1 1 3 QVcaBuslfcSocketPickle QVcaBusIfcSocketPickle is the interface class that provides the mechanisms for the remote connection to the LinCAN driver It enables to connect to the canmond daemon through the QTcpSocket Qt class that provides TCP socket It is assumed that canmond is running on some remote machine on the internet and performs the actual monitoring of CAN bus Canmond is actually a simple TCP IP server that resends all received CAN messages to all clients connected to it QObject connection parse received data stream emit dstribute CANmessageSignal c oO osi SE o a gt sl rd o Figure 7 3 CAN bus m
42. ending of messages that had already been sent to the CAN bus by either of mentioned options application main window or message sequence tool Model that this tool implement does not allow a user to edit particular items but it enables dragging its items data to different application widgets that allow it i e CAN message sequence tool 8 3 Filtering of received and displayed CAN messages notion of filtering covered implementation of two different filtering objects in this application Although they may seem the same they cover two different tasks e Traffic filtering e View filtering Traffic filtering gives a user option to filter the captured data that can be displayed to the user while view filtering allows a user to filter only the view of actually displayed data 56 CHAPTER 8 QCANALYZER DESIGN AND IMPLEMENTATION ISSUES 8 3 1 Traffic filtering To allow a user to filter monitored traffic there was a specialized traffic filtering tool TFT designed Again it was designed with the Qt designer and consists of the same group of widgets as the CAN message sequence or CAN message history tool Main difference between these tools is the model that they implement TF T model stores the set up masks in its QList Actual mask is defined as an implicitly shared object This tool takes a very important position in the whole application architecture It allows a user to define several filtering masks with different roles in the
43. epare CAN messages that can be later sent to the CAN bus Messages are displayed on the rows and divided to particular columns as it is done in QCANalyzer main window traffic view Unlike the MW CAN message model that uses CAN message model implemented by QVCA library tool implements its own model In comparison to the QVCA message model it offers the possibility to edit model s items and drag 8 3 FILTERING OF RECEIVED AND DISPLAYED CAN MESSAGES 55 and drop of item data to different widgets that allow it In order to enable these item properties there had to be set up some special features to this model Each model item has a number of data elements associated with it and each of these can be retrieved by specifying a role to the mode s data function Items can be queried with flags to see if they can be selected dragged or manipulated in any other way enable editing and drag drop of the items particular item flags must return editable flags and drag drop flags for the valid item indexes Plus the model must have setData method implemented 8 2 2 4 Sent message history tool Sent message history tool is a secondary option how a user can send a message sequence to the CAN bus By secondary I mean that this tool was not designed for this purpose and adds this functioniality because of additional user requirements User can send to the CAN bus only the messages that this tool displays So it offers only the possibility of res
44. es and mecha nisms to the large ones that would require complete reprogramming of VCA using the mechanisms and structures provided by Qt At last I had decided for the compromise between these two options complete reprogramming of those parts of VCA that will closely cooperate with the graphical part of our CAN monitoring application According to the Trolltech recommendation to use the letter at the beginning of the objects and applications names developed in Qt I decided to change the name of library to QVCA Qt Virtual CAN API All suggested changes can be divided into three closely related groups that regard e C integration of chosen components e Reimplementation and optimization of VCA s specialized data structures e Extensions and enhancements 7 1 C integration of chosen VCA components C 4 integration of VCA meant the transformation of old data oriented or process oriented C based structures to the object oriented ones goal of object oriented approach is to make the system elements more reusable In addition this approach improves system quality and the productivity of its analysis and design All objects in 37 38 CHAPTER 7 QVCA VCA PORTATION TO QT C are represented as instances of classes Class is the base C data structure It defines particular object abstract characteristics and behaviour QVCA defines several different types of classes Each of them was implemented as
45. essage is added when a new node is connected to the network IDs can have several acceptance filtering masks set These masks have to be kept in a structure that would provide fast lookup adding and removing of an item The speed of these operations is very important considering a situation of a huge CAN net work traffic when every new arriving message ID must be looked up in a data structure that keeps the acceptance filtering masks After this lookup the message is broadcasted to all CAN nodes that can accept it The decision either to refuse or accept new message must be taken in the shortest time AVL GAVL trees satisfy all mentioned requirements VCA implements these structures using the uLan utilities library For better understanding of VCA architecture and message distribution look at the figure 5 2 CAN bus Virtual CAN API LinCAN driver user defined new CAN message arrived callback functions user defined union ID lookup ID mask list message broadcast Figure 5 2 VCA architecture and message distribution 32 CHAPTER 5 VCA VIRTUAL API 5 2 VCA CANopen Protocol Support This part of VCA covers the Object Dictionary OD access as well as Processs Data Object or Service Data Object PDO SDO processing of PDO SDO requests OD is implemented as a GAVL tree of OD objects The functions that enable access to these objects vcaod find object vcaod get value vcaod set value are imp
46. etary code CanFestival focuses on providing an ANSI C platform independent stack that can be implemented as master or slave nodes on PCs Real time IPCs and Micro controllers Supported CanOpen protocols are PDO SDO NMT SYNC Node Guarding Life Guarding Heartbeat and Bootup CanFestival uses Arbracan CAN driver that sup ports only Linux 2 4 and Adlink Board and is slowly deserted by users Recently there was added a new IXXAT VCI driver interface Nevertheless the best way to work with the CanFestival CanOpen stack is to bind it to an existing low level CAN driver Can Festival provides GUI CanFestivalGUI and command line tool CanFestival that help in a process of creating a new CanOpen node and editing Object Dictionary CANFestival GUI screenshot of the application is shown at figure B T is programmed in Qt 2 x and supports many functions of CanFestival in an easy way e Sending Receiving raw CAN Messages e Sending Receiving of PDOs or SDOs e Sending Receiving of NMT e Sending Receiving of Sync Messages Furthermore it provides some additional useful functions e Simulation Mode in this mode you don t need an actual CAN interface e Loading unloading of the device driver Arbracan IXXAT by pushing a button in the GUI module parameters are hardcoded at the moment To modify them you ll have to modify C code and recompile the software I General Public License 2Lesser General Public License 3 2
47. ettings are typed in canmond connection configuration If the name of specified CAN device file does not start with the string dev can or if it can device configuration is set to no application automatically connects to canmond daemon with the connection parameters specified in configuration dialog shown at figure 9 2 Configuration Dialog Configuration Dialog Driver interface Figure 9 2 Configure connection to LinCAN driver Apart from specifying of the connection to the LinCAN driver user can choose if he wants to save automatically all monitored traffic to by him specified log file This option is disabled by default due to possible accumulation of this file This option is useful for short time monitoring Saved file can be later opened and manipulated in the application User can specify the name of the logging file by checking the particular configuration dialog checkbox and typing the name of the file to the Log file line edit Specified settings can be saved by clicking the Save settings dialog button If a monitoring of the CAN bus is in progress user can t change any of the described settings 64 CHAPTER 9 QCANALYZER USER MANUAL 9 2 2 Monitoring When the connection to the LinCAN driver is configured correctly user can start mon itoring either by clicking the Attach to interface button int application mainwindow toolbar or by clicking the Connect in Tools menu or using the predefined keybord shortcut F5 If
48. f such cards is P CAN series of cards produced by Unicontrols driver contains support for more than ten CAN card basic types with the different 23 24 CHAPTER 4 LINCAN LINUX CAN DRIVER combinations of the above mentioned chips Not all card types are held by the OCERA members but Czech Technical University has and tested more SJA1000 type cards and will test some 182527 cards in near future 4 2 Driver Architecture LinCAN provides simultaneous queued communication for more concurrent running applications Driver s architecture is shown for better understanding at figure I T TCP IP VCA API VCA library parser File operations read write ioctl E DS LinCAN driver parser or compiler IO or Memory Figure 4 1 LinCAN architecture Each communication object can be used by one or more applications that is connecting to the communication object internal representation by means of CAN FIFO queues The driver can be configured to provide virtual CAN board software emulated message object to test CAN components on the Linux system without hardware required to connect to the real CAN bus The example configuration of the CAN network components connected to one real or virtual communication object of LinCAN driver is shown at the 4 3 LINCAN SYSTEM LEVEL 25 figure above The communication object is used by the CAN monitor daemon and two CANopen devices im
49. g an intelligent and redundant industrial network The reasons for that are low cost easy stocking reliability high transmission rate high level of error detection and availability of maintanance parts CAN was internationally standardized in 1993 as ISO 11898 1 and comprises two of seven ISO OSI layer reference model Those are data link layer and a part of physical layer CAN provides two basic communication services between the nodes data frame transmission sending of a message and remote trans mission request RTR requesting of a message The data integrity services such as error detection or automatic re transmission of error frames are user transparent which means the CAN chip automatically performs these services CAN offers a multi master hierarchy which allows every node on a bus to be a master and control other nodes Thus if one node is defect the network is still able to work CAN communication is based on a broadcast communicaton mechanism where a sender transmits the messages to all devices the bus receiving devices read the message and then decide if they accept it This 6 CHAPTER 2 CONTROLLER AREA NETWORK CAN is called Acceptance Filtering and and it is shown for better understanding at figure 2 1 CAN CAN CAN CAN Station 1 Station 2 Station 3 Station 4 Consumer Producer Consumer Consumer Local Local Local Intelligence Intelligence Intelligence Figure 2 1 CAN Acceptance Filteri
50. interface between the LinCAN driver and a application that uses it Figure B 1 shows the position of VCA library in the application program that uses LinCAN driver CAN bus library Figure 5 1 Position of VCA in application program VCA can be divided into three parts e Base CAN protocol support e CANopen protocol support e Utility functions 29 30 CHAPTER 5 VCA VIRTUAL API part of that provides base CAN protocol support will be described in more detail because it is closely related to this work Other components of VCA will be men tioned very shortly since they will not be used in prepared CAN monitoring application 5 1 Base CAN Protocol Support This part of VCA provides a basic set of primitive functions used for open close of LinCAN driver and send receive of CAN messages to and from the CAN bus Most of this part is implemented base c and vca pollfdnodecan c source files These two components of VCA are very closely related to a part that allows an application program mer to create and monitor several CAN networks Part that provides this possibility is implemented vca_net c source files Using it can set up several acceptance filtering masks for the particular CAN nodes present in simulated CAN netowrk represented by their IDs Finally VCA provides a logging support used by the whole CAN CANopen component It is implemented in vca_log c mo
51. ion of MW graphical objects is hidden in specialized file 52 CHAPTER 8 QCANALYZER DESIGN AND IMPLEMENTATION ISSUES Ej A ml Figure 8 2 QCANalyzer main window Application main window is shown at figure 8 2 It is organized as a tab widget with two tab pages First tab page provides a traffic view second one provides QCAN plotter tool Monitored traffic is shown in a CAN message table view It displays one particular message on one row Every row is is divided to several columns Each column displays different CAN message field ID flags etc In addition application main window provides another table view that shows the statistics for each received CAN message ID The mechanism that enables to display CAN bus monitored traffic consists of three steps e CAN message reception and distribution e CAN message filtration e CAN message display CAN message reception and distribution is ensured using the mechanisms implemented in QVCA library which QCANalyzer uses to capture the monitored data CAN messages QVCA CAN interface object signals that distribute received CAN messages from the CAN bus to different components of the application are caught by the slot of MW filtering object which performs the filtering of captured before its actual display to a user In this slot user unwanted messages are rejected will not get displayed in a traffic view The 8 2 IMPLEMENTATION 53 ones that do not get filtered are immedia
52. ion will be described very shortly Their detailed description can be found in LinCAN documentation at the OCERA project web pages 5 e open message communication object open system call 44 SUMMARY 27 e close message communication object close system call e read reads received CAN messages from message object e write writes CAN messages to message object for transmission e struct canfilt t structure for acceptance filter setup e IOCTL CANQUE FILTER sets acceptance filter for CAN queue connected to client state e IOCTL CANQUE FLUSH flushes messages from receiption CAN queue 4 4 Summary Authors of the LinCAN driver are Pavel P a Arnaud Westenberg and Tomasz Motylewski Last released version of LinCAN driver is 0 3 The driver was released under GPL license and can be found on several internet resources For further information about LinCAN or about any other component of the OCERA project which it is part of you can visit OCERA project home 6 28 CHAPTER 4 LINCAN LINUX CAN DRIVER Chapter 5 VCA Virtual CAN API API stands for Application Programming Interface It is a source code interface that a library provides to a programmer to support his needs for services to be made of it by his application The OCERA project offers quite an advanced API for the communicaction with the LinCAN driver It is called Virtual CAN API The main idea of was to have only one application
53. ionality To enable a closer look on displayed curve s values tool provides a graph zoomer If a user wants to use the zoomer he has to toggle the Zoom In button and mark re quired plot area Right click on a plot canvas area will return the view to the previous displayed state If a user performed several zooming actions he can return to the original displayed view either by toggling the Zoom In button or by using the combination of Ctrl mouse right click shortcut The tool allows to display several trend curves with different colors and legends specified by the configuration dialog Added curves can be hidden from the plot area and redisplayed back using the legend s toggle buttons placed below the displayed graph Plot area can be cleared by clicking the Clear Plot tool button User can export displayed graphs either to pdf or to SVG format by clicking corresponding tool buttons placed at the top of the plot area Chapter 10 Conclusion In this diploma theses I managed to create a graphical application called QCANalyzer that allows a user to monitor CAN network Using it one can perform a higher analysis of captured data either from the live CAN network or from previously saved files In order to enable the communication of the application with actual CAN hardware some of the results reached byt the OCERA project were used QCANalyzer uses OCERA LinCAN driver as well as the VCA library which provides an advanced API for the communicati
54. its graphical elements generally called widgets to reach the functionality that the application provides Application architecture as well as its implementation depends on functionality requirements that had been determined before the beginning of the implementation process e CAN network traffic display Sending of CAN messages Filtering of received and displayed CAN messages e Plot display of monitored data values e Miscellaneous This chapter will discuss QCANalyzer architecture and the implementation of its partic ular parts with regard to the specified requirements 8 1 QCANalyzer architecture Proposed QCANalyzer architecture keeps the implementation of its graphical objects in dependent from the QVCA library that the application will use for monitoring Therefore it can be divided to two basic parts 49 50 CHAPTER 8 QCANALYZER DESIGN AND IMPLEMENTATION ISSUES e non graphical part it takes care of CAN bus monitoring e graphical part it takes care of display of monitored traffic Each of these parts is running in a different thread Thread is a way how a program forks splits itself into two or more simultaneously running tasks Threads inside one process share some memory while two different processes don t Thread programming is very capable way how to implement a graphical application It preserves the freezing of the user interface and thus improves user interaction with the application while some other
55. k or by clicking the item in Message menu bar Messages are being sent in the order they are displayed in tool s view or in order they were selected by the mouse 9 2 4 3 Traffic filtering tool Message filtering tool gives a user possibility to filter the monitored traffic by the masks created using this tool Tool can be opened from the application main window clicking particular toolbar button item in menu bar or using the shortcut Ctrl T Each newly added mask is appended at the bottom row of tool s table view User can specify the mask and message ID either in decimal or in hexadecimal form Again if the specified values are in hexadecimal form user has to add Ox prefix so they can be correctly interpreted by the tool Screenshot of TFT in use is shown at figure 9 7 9 2 BASIC FUNCTIONALITY 69 Message Filtering Tool m OxEF12 OxFFFF EJ ACTIVE some mask set 0x12 OXFFED M ACTIVE another one 0x12ED 0x11FF12 X ACTIVE Figure 9 7 Traffic filtering tool in use User can define several filtering masks or rules Each new added masks is automati cally created with REJECT action INACTIVE status Reject means that monitored messages that pass set up mask rule will be reject when the status of set up rules is set to ACTIVE User can change the mask status or action by simple checking or unchecking the checkbox in particular status action column As well as the previous tools this tool gives a po
56. led similar way as the save action is Both dialog offer the filtering option of displayed files user can display either text saved 66 CHAPTER 9 QCANALYZER USER MANUAL or binary saved messages Files are opened in new tab page inserted after the QCAN plotted tab page Opened message log is displayed in a table view User can t edit any of the items in it but he can drag the item data to different widgets that allow dropping of dragged data Even the application logging files specified in the application settings can be opened and manipulated this way Closing of opened message log is done by clicking the CLOSE button placed at the top of open log tab page 9 2 4 QCANalyzer specialized tools In addition to previously described functionality application offers some specialized tools e CAN Message sequence tool e Sent message history tool e Traffic filtering tool Implementation of each tool was described in previous chapter This section will show how to use these tools in the application 9 2 4 1 Message sequence tool Message sequence tool is used for sending CAN message sequences It allows a user to prepare messages and then send them to the CAN bus User can send unlimited count of messages Each newly created message is appended at the bottom row of tool s table view Tool allows a user to specify message ID and message flags either in decimal or hexadecimal form as it is done in main window Again if a user wants to spe
57. lel port serial port and PC 104 or an Eth ernet interface like the standalone CANopen Gateway Server EtherCAN Server can be started either in Windows OS or in Linux environment The simplest application pro vided by Port is a simple CAN analyzer also programmed in Tcl tk that can connect to the server and enable sending of messages simple or periodic Supplementary software modules provide extended functionality like service and protocol dependent interpretation of CAN messages 3 2 Open Source Projects Open source projects are usually maintained on a public place usually the internet or some other publicly accesible source file repository where all codes are freely available to everyone for free They are released under public license depending on which it is set what can be done with downloaded source files Many of them are realeased under a license that allows anyone to change it and freely distribute it with their own actual application Unfortunately their documentation is often very poor 16 CHAPTER 3 RELATED PROJECTS 3 2 1 CANFestival ICanFestivallis a CANOpen framework licensed with GPL and Lap dd It provides an ANSI C platform independent CANOpen stack that can be implemented as master or slave nodes on PCs Real time IPCs and Microcontrollers With CanFestival you can e turn any microcontroller or PC into a CANOpen node e edit Object Dictionary and EDS files e use any CAN interface type e link with a propri
58. lemented in vca od c source file The core structure for the SDO processing is in vcasdo fsm c file It implements a CANopen final state machine Wrappper for this state machine is implemented in vca_net c source file PDO processing is implemented using a structure called vcaPDOProcessor t PDO processor knows which OD objects are PDO mapped because it is written in EDS and it can store retrieve them to from OD automatically Further information as well as the documentation of implemented functions can be found on OCERA web pages 4 5 3 Utility Functions This group provides a set of help functions to parse text convert it to number or se rialize CAN messages to human readable form Again Further information as well as documentation of implemented functions can be found on OCERA web pages 4 Chapter 6 Graphical library core of this work concludes creating a graphical application In order to do so I had to decide what graphical library will be used to acheive this goal I was considering only free available or Open Source libraries and their portation to different operating systems After small research I have narrowed my choice to the following possibilities e Toolkit e Qt software developement toolkit Java widget toolkit Each of them will be shortly discussed with regard to development of graphical user interface of CAN monitoring application 6 1 GTK GTK is a multi platform toolkit for
59. lly disconnected switched to Bus off state 2 3 3 Message Frame Formats The CAN protocol defines two basic message frame formats standard and extended There is only one difference between them the length of the message identifier The CAN standard frame has the identifier 11 bits long while CAN extended frame has 29 bit identifier Apart from the data message frames CAN defines 2 communication manage ment frames 2 3 4 Standard Frame Structure of the standard frame is shown at figure 2 3 The frame starts with the SOF start of frame bit which is always dominant It is followed by the arbitration field that contains 11 bit identifier and the RTR bit Remote Transmission Request that distinguishes the data frame from the data request frame This bit has to be dominant in data frame and recessive in data request frame E Aji A ide Identifier T D ro Data CAC EOF FS Ide F RIE K Figure 2 4 CAN message frame After this bit the control field follows containing 2 reserved bits and the 4 bit field that carries the information about the data length that are sent with the message Then 2 3 DATA LINK LAYER 11 the actual data field comes Only 8 bytes of data can be hold by one CAN message frame integrity is guaranteed by 15 bit CRC field After CRC field there is a 1 bit delimiter that separates CRC field from ACK acknowledgement bit that is followed by another delimiter bit ACD acknowledgeme
60. n 71 72 CHAPTER 10 CONCLUSION UNIX machines QCANalyzer provides mechanisms for local and remote monitoring over TCP IP User can connect to any machine on the internet on which canmond daemon is running and perform the monitoring remotely Feature that distringuishes this tool the most from other free available CAN monitoring tools is advanced tool for plotting trans ferred data over CAN network User can start monitoring and after simple configuration of QCAN plotter tool he can watch the transferred data on the real timingly drawn graph Application has been tested on virtually loaded LinCAN driver using the utilities pro vided by the OCERA project Program has not been tested on a real CAN hardware yet but testing results showed that QCANalyzer should appropriately fulfil all requirements that are posed on CAN monitoring tool Testing of the application on real CAN hardware should be performed by the user himself before he decides to use it in a commercial or in other project Future extensions of the application should provide implementation of CANopen pro tocol support QCANalyzer already provides the API that can be used for this porpose The only thing that has to be implemented to enable this support is graphical interface that would provide a user an easy way of manipulation with CANopen devices CANopen support will enable generation of network variables the only assignment requirement that has not been fulfilled in thi
61. ng Acceptance filtering guarantees the common view on transferred data as all devices in the system use the same information Every message starts with a unique identifier within the whole network which defines a content and a priority of the message The highest priority has the identifier of 0 CAN guarantees that the message with the higher priority is delivered preferably in case of a collision of several messages By the identifier you can set the node to accept only for it significant messages CAN offers a sophisticated error detecting mechanisms and re transmission of faulty messages The conformance test for the CAN protocol is defined in the ISO 16845 which guarantees the interchangeability of the CAN chips 2 2 Physical Layer Basic requirement on physical media is the ability to represent a dominant and a reces sive bit value This is possible for electrical and optical media so far Also powerline and wireless transmission is possible The dominant and the recessive bits represent a gener alized equivalence of logical signal levels Their values are not strictly defined and actual representation depends on a concrete realization of physical media For the electrical media the differential output bus voltages are defined in ISO 11898 2 and ISO 11898 3 in SAE J2411 and ISO 11992 With the optical media the recessive level is represented 2 2 PHYSICAL LAYER T by dark and the dominant level by light The most commonly us
62. nicate and replace them in many kinds of works due to several reasons Machines are very often used for doing the jobs that a man is not able to perform If you replace a human being with a lot of machines from which each of them is doing its particular part of job you need to make them communicate with each other to acheive the goal they were designed for Thus when speaking about communication it is very important to be sure about what aspects of communication one is speaking about Communication requires that all parties un derstand a language that is exchanged among them To make the machines understand each other there had to be designed a way how they can exchange information with its surroundings by several methods One of the possibilities to acheive this is to design a communication protocol Communication protocol is a set of standard rules for data representation signalling authentication and error detection required to send an information over a communication channel It is basically following certain rules so that the system works properly There is a lot of procedures that can help you to design your own protocol if you decide so New communication protocol should comprise three main principles Effectiveness Reliability and Resiliency By effectiveness we mean that it needs to be specified in such a way that engineers designers and in some cases software developers can implement and or 1 2 CHAPTER 1 INTRODUCTION use i
63. not be needed if I decided to use GTK Despite all these facts there is a lot of advantages that speaks for Qt Documentation very advanced with many practical examples Class library optimized and tested class data structures not only for GUI pro gramming Developement tools qmake for auto generating of Qt Makefiles Qt Designer powerful tool for designing of user interfaces and many other Signal Slot mechanism thread safe feature of Qt which is very suitable for the 36 CHAPTER 6 GRAPHICAL LIBRARY event driven programming as programming of GUI is decision of using the Qt library for CAN monitoring tool development brought some issues that had to be reconsidered VCA is programmed in C which would not mean any complications generally but in order to ease the creating of the graphical interface it would be better to reimplement some of the VCA components using the structures provided by Qt It would simplify further connecting of to the graphical objects and ensure better cooperation between graphical and non graphical parts of the application Chapter 7 QVCA VCA portation to Qt In order to ease the programming of the graphical application there was decided to reim plement some parts of VCA library This reimplementation meant portation of VCA library to Qt environment More options for porting of VCA to Qt were considered From the small modifictaions concerning the change of some data structur
64. nt delimiter After the ACD bit the EOF end of frame field follows The space between two transmitted messages interframe space is 3 bits long 2 3 5 Extended Frame The message identifier of the extended frame is 29 bits long and is divided into two fields 11 bit identifier as the standard frame and 18 bit identifier extension The difference between standard and extended frames is the IDE bit Accordng to this bit it is decided which message has the priority when accessing the bus in case of collision with the different formats that has the same base identifier 11 bit identifier has always priority over 29 bit identifier therefore it is transmitted as dominant in standard frame and as recessive in case of a 29 bit frame When sending the extended frame a bus latency time is longer in minimum 20 bit times messages in extended format require more bandwidth about 2096 and the error detection performance is lower 2 3 6 Communication Management Frames By the communication management frames we mean the Overload Frame and the Error Frame They are used to manage the communication over the bus concretely for the error detection and signalling and for the requesting of a communication latency The overload frame is usually transmitted by the nodes that are not able to receive and process any data due to their actual load Error frame is used by any node that detects an error on the bus Further information about CAN protocol can
65. of abbreviations I List of Figures 3 2 GanalWorks in use 3 3 Canmonitor in usd 2 1 Acceptance Filterind 2 2 CAN network structure according to ISO 11898 23 CAN data transmitio 2 4 CAN message framg 3 1 CANfestivalGUI in usa 4 1 LinCAN architecturg s 8 5 QCAN plotte 9 3 QCANalyzer in use 5 1 Position of VCA in application program 5 2 VCA architecture and message distributio SAA MESA 8 1 OGANalvzer architecturd 2 2 2 RR 82 OGANalvzer main window 8 3 OCANalvzer CAN message flo 8 1 OCANalyzer traffic filtering 91 OGANalvzer main window RR 9 2 Configure connection to LinCAN drive xi 10 17 19 20 24 9 4 Save message log dialog RR 65 9 5 Message sequence tool in usd 67 9 6 Sent message historv tool in usd 666 68 97 Traffic filtering toolinusd RR 69 98 plotter in usg n 70 xii Chapter 1 Introduction 1 1 Prologue Communication can be defined as a process that allows organisms to exchange informa tion by several methods In modern times communication is not only an issue of living organisms It became a very important part of technical world The world is now filled with the machines of different types that help people to commu
66. on with this driver Application was programmed using Qt development toolkit The use of Qt for developing not only graphical applications is hugely growing in the world of IT Thus the decision of choosing the Qt gave me a chance to learn new advanced technology plus it eased the whole development process of the applica tion since Qt provides a complete framework for cross platform application development Getting familiarized with unknown development framework caused a little slow down of development at the beginning but at last it showed up to be the right solution First some components of VCA library were reprogrammed using this toolkit in order to ease the distribution of captured data to particular application s graphical objects then the actual implementation of QCANalyzer graphical interface followed It required learning of several Qt programming technics that were applied to acheive the functionality require ments claimed at the the beginning Apart from standard functionality of sending and receiving of CAN messages offered by many CAN monitoring tools QCANalyzer offers many other useful solutions It provides an advanced tool for sending CAN message se quences as well as the tool that enables to filter captured traffic Traffic filtering tool gives a user possibility set up several traffic filtering masks with different roles accept reject and states active inactive which slightly resembles iptables firewalls implemented o
67. onitored CAN network can be displayed in ap plication s main window QCAN plotter tab page This tab page provides drawing of 2D plots User can plot several curves at once using this tool Curve that gets displayed using this tool is implemented as a customized Qwt object which is created for every new added message ID Message ID and the byte range from which the actual displayed value of the curve is counted must be specified in order to read the data transferred by particular CAN message Figure 8 5 QCAN plotter 8 5 MISCELLANEOUS 59 Data used for drawing the trend plots are gained in the QCAN plotter slot that is connected to the TFT model signal thus only the data of the messages accepted by TFT can be displayed using this tool shown at figure 8 5 Data transferred by CAN messages are in little endian order They are transformed by this tool to the correct byte order transformed to a number and stored in the curve object s data storage This data storage reimplements another Qwt object that keeps the monitored data in QwtArrays QwtArray is a structure similar to QLIst It offers many useful features for the use in the technical programs for example adding arrays of values apart from adding a single values 8 5 Miscellaneous This group consists of the objects that simplify the user interaction with other application widgets or with the application itself It covers the configuration dialogs and application settings By config
68. onitoring using remote connection to LinCAN driver Figure 3lshows the actual monitoring of CAN bus using the OVcaBuslfcSocketPickle class for the remote connection to the LinCAN driver When a new data is available on the socket for reading QTcpSocket emits the signal which is being caught by corresponding QVcaBusIfcSocketPickle slot connected to it This slot provides the mechanism that parses CAN message from received data stream and then emits it with the signal Again 42 CHAPTER 7 QVCA VCA PORTATION TO QT if a programmer decides to do some other processing with the received message he can just simply connect some other QObject s slot s to this signal Sending the CAN message is implemented using Q TcpSocket write data methods 7 1 2 CAN network classes This group contains only two classes QVcaNet and QVcaNetId QVcaNet class simu lates monitored CAN network It can contain several QVcaNetId objects that repre sent actual CAN nodes connected to this network and offer a possiibility of setting up acceptance filtering masks CAN network nodes and acceptance filtering masks are kept in QVcaNet specialized data structures satisfying several requirements regarding the speed of the manipulation with the items stored in them QVcaNet represents a parent object in the whole QVCA parent children hierarchy When it is destroyed all its chil dren objects are destroyed in its destructor too QVCA architecture is shown at figure
69. plemented by the OCERA CanDev component The actual system dependent driver API is hidden to applications under VCA Virtual CAN API library Each communication object is represented as a character device file The devices can be opened and closed by applications in blocking or non blocking mode LinCAN client application state chip and object configurations are controlled by IOCTL system call One or more CAN messages can be sent or received through write read system calls The data read from or written to the driver are formed from sequence of fixed size structures representing CAN messages 4 3 LinCAN system level 4 3 1 Device Files and Message Structure Each driver is a subsystem which has no direct application level API The operating system is responsible for user space calls transformation into driver functions calls or dis patch routines invocations The CAN driver is implemented as a character device with the standard device node names dev can0 dev canl etc The application program communicates with the driver through the standard system low level input output prim itives open close read write select and ioctl The CAN driver convention of usage of these functions is described in the next subsection The read and write functions need to transfer one or more CAN messages The structure canmsg t is defined for this purpose and is defined in include file can can h It has following fields struct canmsg t 5 int flags
70. ret ciu a generovanie slovn ku sie ov ch premenn ch 111 Abstract This diploma theses deals with the monitoring of CAN protocol based systems The main goal of this work is implementation of monitoring application and sending of test messages in C language environment with the use of Qt software development toolkit Theoretical part of the work describes the basic principles of CAN protocol and discusses several possible suggestions of distribution and filtration of monitored messages into par ticular components of graphical application with the use of connection of this application to CAN driver Practical part describes the design and the implementation of the graph ical application called QCANalyzer which should support analysis of higher communi cation layers for easy stocking in the automotive industry as well as the interpretation and generation of the network dictionary variables iv vi Contents List of picture 1 Introductio 1 2 Motivation 225 225 22 1 3 Problem statement A cm P o 9 12 PCAN Tool a e no 3 22 MSODB o coa een i 3221 CAN Abstraction Laye vil xi N N Ro E 0 GI 10 10 11 11 22032 aan Bee 20 3 2 4 Conclusi n sr se ss OV a Eom Ro s 21 23 en o Br 23 6
71. s Other drawback is that the callback function is strongly coupled to the processing function since it must know which callback function to call In Qt a QObject class which emits a signal neither knows nor cares which slots receive the signal Qt s signals and slots mechanism ensures that if you connect a signal to a slot the slot will be called with the signal s parameters at the right time More information on QObject and Signal Slot mechanism can be found in Trolltech online documentation 10 QVCA implementation provides several classes that were developed from the structures offered by VCA library We can divide these newly designed classes to three groups e CAN interface classes provide the connection to the LinCAN driver and enable sending and receiving of CAN messages e CAN network classes provide CAN message distribution similar to the one implemented in VCA e CANopen classes provide CANopen protocol support 7 1 1 interface classes Basic requirement for the implementation of CAN interface classes was that they should provide a unified connection to the LinCAN driver Apart from the possibility of the local connection QVCA offers a possiblity of the remote connection In order to unify both ways there had to be designed an abstract class from which the particular interface classes would be derived I had decided to call the abstract class QVcaBusIfcAbstract and the derived classes QVcaBusIfcLinCAN resp QVcaBu
72. s work Other possible extension can be implementation of more advanced traffic filtering or sending of periodic CAN messages what can be very useful in automotive applications Another possible extension is implementation of ad vanced project files that would enable an advanced project control and that would allow a user to store all monitoring session configuration and settings in partricular project file In order to speed up the development process of further application extensions official QCANalyzer emnes release is currently being prepared QCANalyzer will be re leased under GPL or LGPL license Anyone will be able to freely download the application source codes and change them for its own possible purposes In the end I would like thank again my tutor Ing Pavel Pisa for his patience help and for many useful suggestions Without him this theses would not reach the quality it has now source code repository on http sourceforge net index php web site for software developers to con trol and manage open source software development Bibliography 1 2 3 4 CAN international users and manufacturers group web site ttp www can cia org El The Vector company web site ttp www vector worldwide com The Peak company web site ttp www peak system com VSCP project web site ttp www vscp org OCERA project web pages ttp www ocera org
73. sIfcSocketPickle All men tioned classes were designed as QObjects to enable their communication using of sig nal slot mechanism 7 1 1 1 QVcaBuslfcAbstract QVcaBusIfcAbstract class provides only the definitions of basic CAN interface program ming features It defines the methods that enable sending and receiving of CAN messages 40 CHAPTER 7 QVCA VCA PORTATION TO QT as well as the signals and slots for CAN message distribution to different parts of QVCA library 7 1 1 2 QVcaBusIfcLinCAN QVcaBusIfcLinCAN class is the interface class that is used for the local connection to the LinCAN driver By the local connection I mean binding the instance of this class to a device file usually dev can present on a local machine through which the actual monitoring is performed Binding the VcaBuslfcLinCAN to the device file is imple mented using Qt QSocketNotifier class that performs the monitoring of the activity on particular device file descriptor This solution replaced the original quite complicated solution of VCA based on using the select function CAN bus a to device file SS connection dev can emit dataReadyToReadSignal emit dstributeCANmessageSignal candela Figure 7 2 CAN bus monitoring using the local connection to LinCAN driver Figure 7 2 shows the actual monitoring of CAN bus using OVcaBuslfeLinC AN class for the local connection to the LinCAN driver Wh
74. send the message again 2 3 2 Data Transmission and The Error Detection Messages transferred using CAN protocol are protected by several mechanism that work concurrently When an error occurs the node that detects it generates an error frame Basic error detection mechanisms implemented in CAN are e Monitoring A transmitter compares a value of an actual transmitted bit with the bit detected on the bus e CRC Cyclic Redundancy Check coding At the end of each message there is a 15 bit CRC code generated from all previous bits of a message e Bit stuffing After five consecutive equal bits the transmitter inserts a stuff bit into the message This stuff bit has a complementary value and is removed by the receivers Apart from the error detection it is used for synchronization 10 CHAPTER 2 CONTROLLER AREA NETWORK CAN e Message frame check message is verified against the format and the size given by the specification e Acknowledge If a message is received by any of the nodes it sends an ACK message back to transmitter this is done by changing ACK bit If a transmitter does not receive an ackowledgement an ACK error is indicated Every node has two internal error counters that determine number of errors when accepting or transmitting messages According to the value of this counter a node can be in one of 3 states Error Active Error passive Bus off If a node generates too many error messages it is automatica
75. simulation mode 3 2 2 VSCP VSCP stands for Very Simple Control Protocol It has been developed for use on low end devices such as microcontrollers It is more than just a protocol It is a complete solution for configuration and control It is very easy to use and very capable It can be used in very demanding control situations VSCP does not assume anything about the 18 CHAPTER 3 RELATED PROJECTS lower level system It works with Ethernet TCP IP Wireless Zigbee Bluetooth CAN GPRS RS 232 USB and everything else user wants It is just a uniform way of describing the systems available Every control situation can be described and implemented using VSCP The VSCP Protocol was from the beginning designed to be used in CAN networks It enables to understand the inner workings of the protocol with just minimal effort and it is supported throughout the industry Even though the protocol is designed for CAN there is no need for its using It can be used equally well in other environments It offers some of the following features e t is free and open for commercial and other use e It has two levels Level I and Level II where level I is designed with CAN as the least common denominator It can be used for TCP IP UDP RF Mains etc e It has globally unique IDs for each node e It has a mechanism to automatically assign a unique ID to a newly installed node e t has software and drivers for Windows and Linux operating systems
76. ssibility to remove all or only by the user selected masks rules It also allows a user to remove all ACTIVE or all INACTIVE masks User can save defined masks to a file that can be later opened by this tool and used in the very same way that was described here When there are no masks specified in the tool or all mask rules status are set to INACTIVE user can define default filtering behaviour by checking unchecking the Accept by default checkbox placed at the bottom of the tool s table view 9 2 5 QCAN plotter QCAN plotter is a plotting tool that allows a user to draw the trend curves of data transferred by the CAN messages with the particular message ID In order to display these data user must configure the plottiing options using its tool s configuration dialog Obligatory fields that must be specified are message ID and the byte range of the data carried by the CAN messages They are marked with the asterisk in tool s configuration dialog user can specify the legend of displayed trend curve and even choose the color of the curve QCANplotter as well as its configuration dialog is shown at figure 9 8 70 CHAPTER 9 QCANALYZER USER MANUAL Clear plot area Configure QCAN plotter QCAN plotter config dialog Figure 9 8 QCAN plotter in use curves are displayed in a plot grid that automatically adjust its scales according to the displaying data Apart from displaying the curves tool offers other funct
77. st important component of this part and probably most important component of the whole library is the mechanism that enables sending and receiving of CAN messages as well as the mechanism that provides the acceptance filtering By these two mechanisms I mean redistributing of received CAN messages to the nodes that can ac cept them according to their acceptance filtering masks Sending and receiving of CAN messages is implemented unsing write read function calls on a particular file descriptor that represents actual CAN bus interface through which the driver communicates with actual CAN hardware measurement card pc etc CAN message distribution in VCA is implemented using the callback function mechanism This mechanism is based on a registration of particular callback function to an event When the event occurs for ex ample a CAN message arrival its registered callback function is called This is quite fast and hugely used in many not only C based applications and libraries Every message that arrives on CAN interface is received and then dsitributed to all nodes in monitored network using this mechanism In order to distribute received CAN messages to particular CAN nodes there had to be designed some specialized data structures that would keep all netowrk IDs and their 5 1 VCA BASE CAN PROTOCOL SUPPORT 31 acceptance filtering masks VCA stores these IDs in generic sorted array GSA list to which the ID of new arriving m
78. t By reliability we mean error detection and correction and by resiliency we mean a readdressation of communication network failure known as topological failure in which a communications link is cut and a degradation below usable quality 1 2 Motivation There is a lot of already designed communication protocols assigned by several standard ization organizations such as ISO etc Although sometimes we don t even know we come to a contact with them every day I am going to talk about the indus trial network communication protocols Such of them are for example Profibus Interbus Lon etc It depends on your application requirements whether you decide to design your own protocol or you will use some of the mentioned protocols Each of them is suitable for different kind of application These protocols are hugely used in several not only industrial applications where humans provides only an unnecessary supervision supervision is needed by many reasons Sometimes the application system is quite huge and manual inspection of an error would be very hard Supervision covers the moni toring of the correct netowrk behaviour and takes care of unexpected events such as corrupted communication eg by mechanical problems incorrect data exchange caused by unknown reasons or configures and provides a diagnosis of network devices Each of these mentioned issues can be done and read from monitored communication thanks to the mechanism
79. tely emitted by another signal that is caught by MW CAN message model slot In this stage of processing new CAN message is appended to the model s QList so all messages are stored in the order they were received from the CAN bus MW CAN message model then provides stored messages to the application main window s table view for display For better understanding of this mechanism look at figure 8 3 QObject connection MW CAN msg model MW filtering object emit acceptedCANmsg append CAN message to model Figure 8 3 QCANalyzer CAN message flow Apart from the MW CAN message model slot signal emitted by the MW filtering object is also caught by a slot of another MW object which takes care of createing message ID statistics CAN message statistics are displayed in a different table on the same tab page as the monitored traffic This require design of a new model which unlike the CAN message model stores its data in QHash Qt generic container similar to QMap ID of new arriving CAN message is checked if the statistics model does not already contain it If not it is added to the model s data QHash and its count is set to one If the model already contains it it increments its count by one 8 2 2 Sending of CAN messages QCAnalyzer offers two possibilities for sending CAN messages to the CAN bus 54 CHAPTER 8 QCANALYZER DESIGN AND IMPLEMENTATION ISSUES e Sending of a single CAN message e Sending of CAN message sequences
80. that is provided by a particular communication protocol To conclude by supervision we mean analysis of a communication over the communication channel among particular parties To acheive this goal there is a need to use or create a specialized tool that enables an easy analysis and high level inspection of the communication itself 1 3 Problem statement This work should support a monitoring of one of the above mentioned industrial protocols called CAN Controller Area Network It will provide a mechanism that will enable creating an application supposingly with an intuitive GUI Graphical User Interface This application will ease the analysis of the communication over the CAN bus In or der to create such an application there had to be designed a driver that would enable a 1 3 PROBLEM STATEMENT 3 communication of the particular hardware with this application program Commercial vendors usually offer their own CAN hardware with their own driver and actual monitor ing aplication or an application with the drivers that support only very small group of CAN hardware usually their own This provides a comfort and a support of the product by its vendor but on the other hand impossibility of adjusting it to your needs Plus there is also quite an important aspect for deciding to design your own application the prize of commercial products Before I started to work on this diploma theses I had researched the internet which is a norm
81. the top of the message table view Name typed in this line edit is immediately reflected in tool s window title 9 2 4 2 Sent message history tool Message history tool gives a user possibility to keep the track of messages sent either by the message sequence tool or from the application main window Apart from reviewing of sent message history tool enables to resend either all or only selected messages that it stores and displays as it is shown at figure 0 6 68 CHAPTER 9 QCANALYZER USER MANUAL OxAED 0x4 1 15 08 11 41 PM 123F OxAED 0 4 1 15 08 11 41 123F Ox34EF 0x0 1 15 08 11 41 PM 123 0x34EF 0x0 1 15 08 11 41 PM 123E 0x34 0x6 1 15 08 11 41 PM 12345E 0x34 0x6 1 15 08 11 41 PM 12345E 0x159 0x4 1 15 08 11 41 PM 1234 0 159 0 4 1 15 08 11 41 PM 1234 Figure 9 6 Sent message history tool in use Message history can be saved either in text or in binary form Saved files can be reopened and used again messages can be dragged from this tool and dropped to any opened message sequence tool in which they can be edited and send to the CAN bus Sent message history tool enables to remove either all of the displayed messages or only the ones selected by the mouse As well as message sequence tool this tool provides a possibility of sending and removing of displayed messages by clicking corresponding item in context menu called by the mouse right button clic
82. uration dialogs I mean the dialog that allows a user to config monitoring options and the dialog that alows a user to configure QCAN plotter drawing options Both dialogs were designed by Qt designer Their sginals are connected to particular slots implemented as the methods of MW Their use will be described in user manual Application settings are stored in a special object that inherits one of the most useful Qt object QSettings QSettings provides platform independent application settings QSettings is a wrapper around different OS technologies Windows stores the application settings in the system registry MAC OS X in XML preferences files and UNIX systems in INI files The use of QSettings class is very simple and intuitive application programmer specifies only a couple setting key that are added by QSettings object to the application settings file All other processing is automatically taken care of behind the scene by QSettings object itself Application settings are loaded when the programm is executed Apart from graphical settings of QCANalyzer widgets to restore position and size of the application main window they store monitoring session options too 60 CHAPTER 8 QCANALYZER DESIGN AND IMPLEMENTATION ISSUES Chapter 9 QCANalyzer User manual QCANalyzer does not contain any installation script yet It has to be compiled and built directly from the given source codes 9 1 Compilation an building the QCA Nalyzer There
83. y configuration file from which the application reads its settings Configuration file is specified as a program argument If the specified file does not exist application will load last used settings If the configuration file with last settings does not exist default application settings are loaded Attach to Interface monitoring Configure settings filtering tool CAN message sequence tool Sent message history tool Send CAN message OR Figure 9 1 QCANalyzer main window 9 2 1 Connection to the LinCAN driver Before the user starts to monitor the CAN bus he should check or configure the settings for actual monitoring session This can be done using the QCANalyzer configuration dialog Dialog is opened either by clicking particular icon in toolbar or by clicking Con 9 2 BASIC FUNCTIONALITY 63 figure Settings in Tools menu from the application main window menu bar or using the configuration shortcut Ctrl D Configuration dialog allows a user to edit following monitoring session settings e Driver interface connection e Logging User can configure the connection of the application to the LinCAN driver through ma nipulating the dialog s widgets Application connects by default to canmond daemon which supposingly runs on remote machine to which the application is connecting over TCP IP If a user specifies CAN device file in configuration dialog local connection will be used no matter what s

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