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NI-CAN User Manual - National Instruments

1. 2 9 Step 5 Close Objects 2 9 Checking Status of Function Calls 2 10 NI CAN Status Format 2 10 Error and Warning Indicators Severity 2 10 Code 2 10 Qualifier 2 11 Checking Status in LabVIEW 2 11 Checking Status in C 2 12 Chapter 3 NI CAN Programming Techniques Using Queues 3 1 State Transitions 3 1 Empty Queues 3 1 Full Queues 3 2 Disabling Queues
2. 3 2 Using the CAN Network Interface Object with CAN Objects 3 2 Detecting State Changes 3 4 Chapter 4 Application Examples Example 1 Using CAN Objects 4 2 Example 2 Simple CAN Bus Analyzer 4 4 Example 3 Interactive CAN Example 4 6 Contents National Instruments Corporation vii NI CAN User Manual Chapter 5 NI CAN Configuration Utility Overview 5 1 Starting the NI CAN Configuration Utility in Windows 98 95 5 2 Starting the NI CAN Configuration Utility in Windows NT 5 3 Configuring Objects with the NI CAN Configuration Utility 5 4 Select the Port 5 5 Select the CAN Network Interface Object Name 5 5 Specify the Configuration Attributes 5 5 Configure t
3. 1 13 Application Examples 1 13 Interaction of Software Components with Your Application 1 14 Contents NI CAN User Manual vi www natinst com Chapter 2 Developing Your Application Choosing Your Programming Method 2 1 Choosing a Method to Access the NI CAN Software 2 1 G Language LabVIEW Function Library 2 1 C C Language Interfaces 2 1 Direct Entry Access 2 2 Choosing Which NI CAN Objects to Use 2 4 Using CAN Network Interface Objects 2 4 Using CAN Objects 2 5 Programming Model for NI CAN Applications 2 6 Step 1 Configure Objects 2 8 Step 2 Open Objects 2 8 Step 3 Start Communication 2 8 Step 4 Communicate Using Objects
4. The application calls ncConfig to configure the CAN Network Interface Objects for both ports CAN0 and CAN1 Normally this configuration would be handled using the NI CAN Configuration utility but ncConfig is used instead to keep the example self contained 2 The application calls ncConfig to configure the CAN Objects for both ports CAN0 STD5 and CAN1 STD5 Once again such configuration would normally be handled using the NI CAN Configuration utility 3 The application calls ncOpenObject to open the two CAN Objects 4 The application calls ncWrite for CAN1 STD5 This call starts the periodic transmission of data For this example the same data is transmitted every period 5 The application calls ncWaitForState for CAN1 STD5 in order to wait for the NC_ST_WRITE_SUCCESS state This state is set when the first CAN frame is successfully transmitted to the other CAN Object 6 The application calls ncWaitForState for CAN0 STD5 in order to wait for the NC_ST_READ_AVAIL state This state is set when a CAN frame is received from the other CAN Object 7 The application calls ncRead to read data for CAN0 STD5 The data contains the value written in step 4 as well as a timestamp of when the value arrived 8 The application loops back to step 6 for a total of 10 periods Each period step 6 waits one second before the next data value is received 9 When all 10 loops complete both CAN Objects are closed using ncClos
5. When receiving data from the device if your only requirement is to obtain the most recent data you are not required to wait for the NC_ST_READ_AVAIL state If this is the case you can set the read queue length of the CAN Object to zero during configuration so that it only holds the most recent data bytes Then you can use the ncRead function as needed to obtain the most recent data bytes received Step 4b Read Data Read the data bytes using ncRead For CAN Objects that receive data frames ncRead returns a timestamp of when the data was received followed by the actual data bytes the number of which you configured in Step 1 Steps 4a and 4b should be repeated for each data value you want to read from the CAN device Step 5 Close Objects When you are finished accessing the CAN devices close all objects using the ncCloseObject function before you exit your application Chapter 2 Developing Your Application NI CAN User Manual 2 10 www natinst com Checking Status of Function Calls Each NI CAN function returns a value that indicates the status of the function call Your application should check this status after each NI CAN function call The following sections describe the NI CAN status and how you can check it in your application NI CAN Status Format To provide the maximum amount of information the status returned by NI CAN functions is encoded as a signed 32 bit integer The format of this integer is shown in Fig
6. With its growing popularity in automotive and industrial applications CAN has been increasingly used in a wide variety of diverse applications Usage in systems such as agricultural equipment nautical machinery medical apparatus semiconductor manufacturing equipment and machine tools testify to the incredible versatility of CAN CAN Identifiers and Message Priority When a CAN device transmits data onto the network an identifier that is unique throughout the network precedes the data The identifier defines not only the content of the data but also the priority A CAN identifier along with its associated data is often referred to as a CAN Object When a device transmits a message onto the CAN network all other devices on the network receive that message Each receiving device performs an acceptance test on the identifier to determine if the message is relevant to it If the received identifier is not relevant to the device such as RPM received by an air conditioning controller the device ignores the message When more than one CAN device transmits a message simultaneously the identifier is used as a priority to determine which device gains access to the network The lower the numerical value of the identifier the higher its priority Figure 1 1 shows two CAN devices attempting to transmit messages one using identifier 647 hex and the other using identifier 6FF hex As each device transmits the 11 bits of its identifier it ex
7. 3 1 to 3 2 ncWaitForState function 2 9 3 4 NI CAN Configuration utility 5 1 to 5 8 accessing online help 5 5 CAN Network Interface Object name selecting 5 5 CAN Object configuration 5 6 to 5 8 adding configurations 5 7 exiting CAN Object dialog box 5 8 removing configurations 5 7 selecting CAN Object 5 6 specifying attributes 5 7 completing configuration 5 8 configuration attributes specifying 5 5 Index NI CAN User Manual I 4 www natinst com missing CAN Interface in Windows NT C 1 overview 1 12 5 1 port selection 5 5 Settings dialog box figure 5 4 starting Windows 98 95 5 2 Windows NT 5 3 NI CAN Diagnostic utility failures Windows 98 95 B 3 to B 4 Windows NT C 1 to C 2 purpose 1 12 NI CAN object hierarchy 1 10 to 1 12 applying NI CAN objects figure 1 11 simple CAN device network application figure 1 10 NI CAN software See also programming components 1 12 to 1 14 driver and utilities 1 12 firmware image files 1 13 interaction with your application figure 1 14 language interface files 1 13 determining version installed Windows 98 95 B 5 Windows NT C 3 independent design 1 9 object hierarchy 1 10 to 1 12 applying NI CAN objects figure 1 11 simple CAN device network application figure 1 10 object oriented design 1 9 problem encountered See also troubleshooting and common questions Windows 98 95 B 5 to B 6 Windows NT C 3 to C 4 uninstalling A 3 to A 4 som
8. Start of Frame is a single bit 0 that marks the beginning of a CAN frame S S Device B Loses Arbitration Device A Wins Arbitration and Proceeds Device A ID 11001000111 647 hex Device B ID 11011111111 6FF hex S Start Frame Bit Standard Frame Format Extended Frame Format S O F R T R I D E A C K 11 Bit Arbitration ID DLC 0 8 Data bytes 15 Bit CRC End of Frame S O F I D E R T R High 11 Bits of Arbitration ID Low 18 Bits of Arbitration ID DLC 0 8 Data bytes A C K 15 Bit CRC End of Frame Chapter 1 Introduction NI CAN User Manual 1 4 www natinst com Arbitration ID The arbitration ID fields contain the identifier for a CAN frame The standard format has one 11 bit field and the extended format has two fields which are 11 and 18 bits in length In both formats bits of the arbitration ID are transmitted from high to low order Remote Transmit Request RTR The Remote Transmit Request bit is dominant 0 for data frames and recessive 1 for remote frames Data frames are the fundamental means of data transfer on a CAN network and are used to transmit data from one device to one or more receivers A device transmits a remote frame to request transmission of a data frame for the given arbitration ID The remote frame is used to request data from its source device rather than waiting for the data source to transmit the data on its own Identifier Extensi
9. natinst com National Instruments and NI CAN are trademarks of National Instruments Corporation Product and company names mentioned herein are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing for a level of reliability suitable for use in or in connection with surgical implants or as critical components in any life support systems whose failure to perform can reasonably be expected to cause significant injury to a human Applications of National Instruments products involving medical or clinical treatment can create a potential for death or bodily injury caused by product failure or by errors on the part of the user or application designer Because each end user system is customized and differs from National Instruments testing platforms and because a user or application designer may use National Instruments products in combination with other products in a manner not evaluated or contemplated by National Instruments the user or application designer is ultimately responsible for verifying and validating the suitability of National Instruments products whenever National Instruments products are incorporated in a system or application including without limitation the appropriate design process and safety level of such system or application National Instruments Corporation v NI C
10. wiring failures occur The transceiver solves many common and frequent wiring problems such as poor connectors and also overcomes short circuits of either transmission wire to ground or battery voltage or the other transmission wire The transceiver resolves the fault situation without involvement of external hardware or software On the detection of a fault the transceiver switches to a one wire transmission mode and automatically switches back to differential mode if the fault is removed Special resistors are added to the circuitry for the proper operation of the fault tolerant transceiver The values of the resistors depend on the number of nodes and the resistance values per node For guidelines on selecting the resistor refer to the cabling appendix of your NI CAN getting started manual Because the low speed transceiver switches to a fault tolerant mode on fault detection and continues to maintain communications NI CAN provides a special attribute NC_ATTR_LOG_COMM_ERRS which when set to NC_TRUE enables the reporting of such errors in the Read queue of the Network interface rather than in the Status returned from a function call The default value of this attribute is NC_FALSE for high speed interface Refer to the CAN network interface object attributes section in the NI CAN Programmer Reference Manual for details on how to use this attribute Chapter 1 Introduction National Instruments Corporation 1 9 NI CAN User Manual
11. After selecting OK or Cancel you are returned to the Settings tab so you can complete the configuration for the CAN interface Complete the Configuration When you have finished using the NI CAN Configuration utility click OK to close the dialog box and saves any changes you have made or click Cancel to close the dialog box without saving any changes you have made National Instruments Corporation A 1 NI CAN User Manual A Uninstalling the Hardware and Software This appendix describes how to uninstall the CAN hardware and the NI CAN software Uninstalling the CAN Hardware from Windows 98 95 Before physically removing the CAN hardware from the computer you must remove the hardware information from the Windows Device Manager To remove the hardware information from Windows 98 95 double click on the System icon in the Control Panel which you can open from the Settings selection of the Start menu Select the Device Manager tab in the System Properties dialog box that appears click the View devices by type button at the top of the Device Manager tab and double click on the National Instruments CAN Interfaces icon To remove an interface select it from the list of interfaces under National Instruments CAN Interfaces as shown in Figure A 1 and click the Remove button Appendix A Uninstalling the Hardware and Software NI CAN User Manual A 2 www natinst com Figure A 1 Selecting an Interface to Remove from Windows 9
12. CAN Object to transmit different speeds the test engineer can verify that the speed display always shows the correct speed To use NI CAN to test the speed sensor the engineer uses a CAN Object to simulate the role of the speed display This CAN Object is configured to receive speeds from the sensor and display them By using this CAN Object to receive and display different speeds the test engineer can connect the speed sensor to a real engine then verify that the speeds it transmits are correct To learn the basics of CAN Object usage prior to testing the actual devices the test engineer writes a simple example to implement both CAN Objects To do this he uses a two port CAN interface such as the AT CAN 2 He connects the top port of the card to the bottom port using a cable One port plays the role of the simulated speed display and the other port plays the role of the simulated speed sensor Chapter 4 Application Examples National Instruments Corporation 4 3 NI CAN User Manual Example 1 configures one CAN Object to receive data and configures another CAN Object to transmit data Both CAN Objects use arbitration ID 5 The data is transmitted every second so the test engineer can view each period s data as well as its timestamp Once the engineer completes the example he can change it for testing of each device by using one CAN Object at a time The following steps correspond to the program flow chart in Figure 4 1 1
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14. Common Questions This appendix describes how to troubleshoot problems with the NI CAN software for Windows NT and answers some common questions Missing CAN Interface in the NI CAN Configuration Utility The NI CAN Configuration utility contains configuration information for all of the CAN hardware it is aware of that is installed in your system To start the NI CAN Configuration utility double click on NI CAN Configuration under Start Settings Control Panel If the CAN interface you are looking for is not listed under National Instruments CAN Interfaces the CAN interface is not properly installed For National Instruments CAN hardware this problem indicates that the interface is not physically present in the system If the interface is firmly plugged into its slot and the problem persists contact National Instruments Troubleshooting Diagnostic Utility Failures The following sections explain common error messages generated by the NI CAN Diagnostic utility No Resources Assigned This error occurs if you have not assigned resources to the CAN interface Refer to Chapter 2 Installation and Configuration in your NI CAN getting started manual for information on assigning memory and interrupt resources to the CAN interface Appendix C Windows NT Troubleshooting and Common Questions NI CAN User Manual C 2 www natinst com Memory Resource Conflict This error occurs if the memory resource assigned to a CAN interface conflic
15. NI CAN Software Overview Independent Design The NI CAN Application Programming Interface API like most National Instruments APIs is largely independent of operating system and programming language You can use NI CAN in a wide variety of programming environments including LabVIEW and C programming environments such as LabWindows CVI Applications written for NI CAN are also portable across different operating systems such as Windows 98 95 and Windows NT In addition to being independent of operating system and programming language NI CAN is designed to be largely independent of a specific device network protocol Device network independence means that where possible terminology specific to CAN alone is avoided so that the API can be expanded later to support higher level protocols based on CAN Examples of such protocols include DeviceNet Smart Distributed System SDS and CANopen Device network independence largely applies to terminology such as function names and in no way limits access to the CAN network For example the function provided to read data from a CAN frame is called ncRead as opposed to a name specific to CAN such as ncReadCanFrame Object Oriented Design NI CAN often uses object oriented terminology and concepts Object oriented terminology provides an excellent model for describing device networks in terms that are easy to understand In object oriented terminology the term class describes a classification
16. Object Configure CAN Network Interface Object ncConfig ncOpenObject Yes No No 3 Configure Periodic Transmit Configure CAN Object ncConfig Yes Write Selected ncWrite 4 Open CAN Object ncOpenObject 5 Write to CAN Network Interface Object Read from CAN Network Interface Object 6 Yes No No No Read Successful 8 Insert Frame into Array Yes Configure Periodic Transmit ncWrite 7 Write to CAN Object Yes NI CAN Error or Stop Button ncCloseObject 9 Close Objects ncRead National Instruments Corporation 5 1 NI CAN User Manual 5 NI CAN Configuration Utility This chapter describes the NI CAN Configuration utility you can use to configure the objects of the NI CAN software Overview The Windows 98 95 NI CAN Configuration utility is integrated into the Windows Device Manager The Windows NT NI CAN Configuration utility is integrated into the Windows NT Control Panel You can use the NI CAN Configuration utility to view or modify the configuration of NI CAN objects For each CAN interface in your system you can use the NI CAN Configuration utility to configure each CAN port as a CAN Network Interface Object For example you can configure the two ports of an AT CAN 2 as CAN0 and CAN1 and you can initialize configuration attributes such as baud rate For each CAN Network Interface Object you can use the NI CAN Configuration utility to create
17. Object A CAN identifier along with its associated data CAN remote frame Frame used to request data for a CAN Object from a remote node the RTR bit is set and the data length indicates the amount of data desired but no data bytes are included class A set of objects that share a common structure and a common behavior connection An association between two or more nodes on a network that describes when and how data is transferred controller A device that receives data from sensors and sends data to actuators in order to hold one or more external real world variables at a certain level or condition A thermostat is a simple example of a controller D device See node device network Multi drop digital communication network for sensors actuators and controllers DLL Dynamic link library DMA Direct memory access Glossary National Instruments Corporation G 3 NI CAN User Manual E error active A CAN node is in error active state when both the receive and transmit error counters are below 128 error counters Every CAN node keeps a count of how many receive and transmit errors have occurred The rules for how these counters are incremented and decremented are defined by the CAN protocol specification error passive A CAN node is in error passive state when one or both of its error counters increment above 127 This state is a warning that a communication problem exists but the node is still participat
18. Objects The flowchart in Figure 3 1 shows the steps performed by NI CAN when a CAN frame is received Figure 3 1 Flowchart for CAN Frame Reception Yes No Arbitration ID Handled by an Open CAN Object No Yes Standard Extended Data Frame Standard or Extended Frame No Standard Comparator Disabled NC_CAN_ARBID_NONE No Extended Comparator Disabled NC_CAN_ARBID_NONE Masked Arbitration ID Equal to Standard Comparator Masked Arbitration ID Equal to Extended Comparator Yes Yes Yes Frame Received Place Frame Into Read Queue of CAN Network Interface Object CAN Object Uses Frame CAN Network Interface Object Frame Ignored Frame Ignored Apply Extended Mask Apply Standard Mask No No Frame Ignored Frame Ignored Frame Ignored Chapter 3 NI CAN Programming Techniques NI CAN User Manual 3 4 www natinst com The decisions in Figure 3 1 are generally performed by the on board CAN communications controller chip Nevertheless if you intend to use CAN Objects as the sole means of receiving CAN frames it is best to disable all frame reception in the CAN Network Interface Object by setting the comparator attributes to NC_CAN_ARBID_NONE By doing this the CAN communications controller chip is best able to filter out all incoming frames except those handled by CAN Objects Detecting State Changes You can detect state changes for an object using one of the followin
19. Troubleshooting Diagnostic Utility Failures section of this appendix for specific information about what might cause the NI CAN Diagnostic utility to fail If you have already completed the troubleshooting steps contact National Instruments How many CAN interfaces can I configure for use with my NI CAN software for Windows 98 95 The NI CAN software for Windows 98 95 can be configured to communicate with up to 10 CAN interfaces Are interrupts required for the NI CAN software for Windows 98 95 Yes one interrupt per interface is required Appendix B Windows 98 95 Troubleshooting and Common Questions NI CAN User Manual B 6 www natinst com How do I use an NI CAN language interface For information about using NI CAN language interfaces refer to Chapter 2 Developing Your Application How do I use NI CAN from within LabVIEW For information about using NI CAN from within LabVIEW refer to Chapter 2 Developing Your Application Why does the uninstall program leave some components installed The uninstall program removes only items that the installation program installed If you add anything to a directory that was created by the installation program the uninstall program does not delete that directory because the directory is not empty after the uninstallation You will need to remove any remaining components yourself National Instruments Corporation C 1 NI CAN User Manual C Windows NT Troubleshooting and
20. and modify CAN Objects The online help includes all of the information that you need to properly configure the objects of the NI CAN software The NI CAN Configuration utility provides an easy mechanism for configuring the objects used by your application By configuring objects with the NI CAN Configuration utility your application can open the objects and begin using them If you do not want your application to rely on the NI CAN Configuration utility it must call the ncConfig function for every object you use The ncConfig function specifies values for all of an object s configuration attributes The configuration attributes you specify using ncConfig override any configuration attributes you have specified using the NI CAN Configuration utility For more information on ncConfig refer to the NI CAN Programmer Reference Manual Chapter 5 NI CAN Configuration Utility NI CAN User Manual 5 2 www natinst com Starting the NI CAN Configuration Utility in Windows 98 95 To start the NI CAN Configuration utility on Windows 98 95 follow these steps 1 Double click on the System icon in the Control Panel which can be opened from the Settings selection of the Start menu 2 Select the Device Manager tab in the System Properties dialog box that appears 3 Click on the View devices by type button at the top of the Device Manager tab and double click on National Instruments CAN Interfaces 4 In the list of installed interface
21. description of ncOpenObject in the NI CAN Programmer Reference Manual After entering the arbitration ID click on the Add button to add the CAN Object to the list You may then specify the attributes for the CAN Object To cancel the addition of the new CAN Object click on the Cancel button Remove CAN Object Configurations If you want to remove a CAN Object configuration select the object from the CAN Objects list then click on the Remove button Specify the Configuration Attributes After adding a new CAN Object or selecting an existing CAN Object you can use the controls in the Attributes section to specify the configuration attributes for the CAN Object Within the Attributes section you can use the Default button to initialize the attribute controls with acceptable default values If you need help with a particular control click on the question mark near the upper right corner of the dialog box then click on the control in question to view the context sensitive online help Alternately you can right click the mouse on the control and then select What s This from the pop up menu that appears Chapter 5 NI CAN Configuration Utility NI CAN User Manual 5 8 www natinst com Exit the CAN Object Setting Dialog Box When you are finished configuring the CAN Objects click on OK to close the dialog box and save any changes you have made or click Cancel to close the dialog box without saving any changes you have made
22. periodically transmit a data frame for a specific arbitration ID The CAN Object transmits the same data bytes repetitively until different data is provided using ncWrite This configuration is useful for simulation of a device that periodically transmits its data such as simulation of an automotive sensor This configuration is also useful for devices that expect to periodically receive data for a particular arbitration ID to respond with data using a different arbitration ID such as a device containing analog inputs and outputs You can configure a CAN Object to watch for unsolicited data frames received for its arbitration ID then store that data in the CAN Object s read queue A watchdog timeout is provided to ensure that incoming data is received periodically This configuration is useful when you want to apply a timeout to data received for a specific arbitration ID and store that data in a dedicated queue If you do not need to apply a timeout for a given arbitration ID it is often preferable to use the CAN Network Interface Object to receive that data You can configure a CAN Object to periodically poll for data by transmitting a remote frame and receiving the data frame response This configuration is useful for communication with devices that require a remote frame to transmit their data You can configure a CAN Object to transmit a data frame whenever it receives a remote frame for its arbitration ID You can use th
23. settings list on the Resources tab to verify that the CAN interface was not assigned a Memory Range To solve this problem free up an 8 KB Memory Range such as D0000 to D1FFF hex that is being used by another device in the system Code 15 The CAN interface was not assigned an Interrupt Request level If your computer does not have any available Interrupt Request levels Windows 98 95 might configure your CAN interface without an Interrupt Request level The NI CAN software cannot function without an Interrupt Request level Another way to verify this problem is to look at the Resource settings list on the Resources tab to verify that the CAN interface was not assigned an Interrupt Request level To solve this problem free up an Interrupt Request level that is being used by another device in the system Code 22 The CAN interface is disabled To enable the CAN interface check the appropriate configuration checkbox in the Device Usage section of the General tab Code 24 The CAN interface is not present or the Device Manager is unaware that the CAN interface is present To solve this problem select the interface in the Device Manager and click on the Remove button Next click the Refresh button At this point the system rescans the installed hardware and the CAN interface should show up without any problems If the problem persists contact National Instruments Code 27 Windows 98 95 was unable to assign the C
24. uninstall program removes only items that the installation program installed If you add anything to a directory that was created by the installation program the uninstall program does not delete that directory because the directory is not empty after the uninstallation You will need to remove any remaining components yourself After the uninstall program completes select OK then restart your computer If you want to reinstall the hardware and software refer to the getting started manual National Instruments Corporation B 1 NI CAN User Manual B Windows 98 95 Troubleshooting and Common Questions This appendix describes how to troubleshoot problems with the NI CAN software for Windows 98 95 and answers some common questions Troubleshooting Windows Device Manager Problems The Windows Device Manager contains configuration information for all of the CAN hardware it is aware of that is installed in your system To start the Windows Device Manager double click on the System icon under Start Settings Control Panel In the System Properties box that appears select the Device Manager tab and click the View devices by type radio button at the top of the tab If there is no National Instruments CAN Interfaces item and you are certain you have a CAN interface installed refer to the No National Instruments CAN Interfaces section of this appendix If the National Instruments CAN Interfaces item exists but the CAN interface
25. 3 Figure 1 3 Simple CAN Device Network Application The pushbutton device transmits the state of the button in a CAN data frame with standard arbitration ID 13 The frame data consists of a single byte zero if the button is off one if the button is on For an NI CAN application to obtain the current state of the pushbutton it transmits a CAN remote frame with standard arbitration ID 13 The pushbutton device responds to this remote transmission request by transmitting the button state in its CAN data frame Network Interface User Application LED Device Pushbutton Device Arbitration ID 5 Data Frame Arbitration ID 13 Data Frame Arbitration ID 13 Remote Frame Chapter 1 Introduction National Instruments Corporation 1 11 NI CAN User Manual The LED device expects to obtain the state of the LED from a CAN data frame with standard arbitration ID 5 It expects the frame data to consist of a single byte zero to turn the light off one to turn the light on Figure 1 4 shows how NI CAN objects encapsulate access to this CAN device network The ovals in Figure 1 4 indicate NI CAN objects and the dotted lines indicate what each object encapsulates Figure 1 4 Applying NI CAN Objects to the Example in Figure 1 3 The CAN Network Interface Object encapsulates the entire CAN network interface Its attributes are used to configure settings that apply to the network interface as a whole For example the CAN Network I
26. 5 to 2 6 detecting state changes 3 4 interaction of NI CAN software with your application figure 1 14 model for NI CAN applications 2 6 to 2 9 closing objects 2 9 communicating using objects 2 9 configuring objects 2 8 general program steps figure 2 7 opening objects 2 8 reading data 2 9 starting communication 2 8 queues 3 1 to 3 2 disabling queues 3 2 empty queues 3 1 to 3 2 full queues 3 2 state transitions 3 1 Q questions See troubleshooting and common questions queues 3 1 to 3 2 disabling queues 3 2 empty queues 3 1 to 3 2 full queues 3 2 read and write queues 3 1 state transitions 3 1 R reading data 2 9 Remote Transmit Request RTR field 1 4 S Settings dialog box figure 5 4 simpanlz c source code 4 1 Smart Distributed System SDS 1 9 SOF Start of Frame field 1 3 standard for CAN 1 1 Start of Frame SOF field 1 3 state changes detecting 3 4 state transitions queues 3 1 status of function calls checking 2 11 to 2 12 C and C 2 12 LabVIEW 2 11 to 2 12 NI CAN status format 2 10 to 2 11 code 2 10 error warning indicators severity 2 10 qualifier 2 11 stuff error 1 6 Index NI CAN User Manual I 6 www natinst com T technical support D 1 to D 2 telephone and fax support D 2 troubleshooting and common questions Windows 98 95 B 1 to B 6 CAN hardware problem encountered B 4 common questions B 5 to B 6 interrupt resource conflict B 4 memory r
27. 8 95 After you remove the appropriate CAN interface information from the Device Manager you should shut down Windows power off your computer and physically remove the CAN interfaces Uninstalling the CAN Hardware from Windows NT Because the current version of Windows NT does not maintain hardware information for the CAN interfaces you need only to physically remove the CAN interfaces from your computer Power off your computer and physically remove the CAN interfaces Appendix A Uninstalling the Hardware and Software National Instruments Corporation A 3 NI CAN User Manual Uninstalling the NI CAN Software Before uninstalling the NI CAN software you should remove all CAN interface hardware from your computer Complete the following steps to remove the NI CAN software 1 Run the Add Remove Programs applet from the Control Panel A dialog box similar to the one in Figure A 2 appears This dialog box lists the software available for removal Figure A 2 Add Remove Programs Properties Dialog Box Appendix A Uninstalling the Hardware and Software NI CAN User Manual A 4 www natinst com 2 Select the NI CAN software you want to remove and click the Add Remove button The uninstall program runs and removes all folders utilities device drivers DLLs and registry entries associated with the NI CAN software Figure A 3 shows the results of a successful uninstallation Figure A 3 NI CAN Uninstallation Results The
28. AN User Manual Contents About This Manual How To Use the Manual Set ix Conventions ix Related Documentation x Chapter 1 Introduction CAN Overview 1 1 History and Usage of CAN 1 1 CAN Identifiers and Message Priority 1 2 CAN Frames 1 3 Start of Frame SOF 1 3 Arbitration ID 1 4 Remote Transmit Request RTR 1 4 Identifier Extension IDE 1 4 Data Length Code DLC 1 4 Data Bytes 1 4 Cyclic Redundancy
29. AN interface any resources To solve this problem free up system resources by disabling other unnecessary hardware so that enough resources are available for the CAN interface The resources required for a single CAN interface are an Interrupt Request level and an 8 KB physical Memory Range such as D0000 to D1FFF hex Troubleshooting Diagnostic Utility Failures The following sections explain common error messages generated by the NI CAN Diagnostic utility Memory Resource Conflict This error occurs if the memory resource assigned to a CAN interface conflicts with the memory resources being used by other devices in the system Resource conflicts typically occur when your system contains legacy boards that use resources that have not been reserved properly with the Device Manager If a resource conflict exists write down the memory Appendix B Windows 98 95 Troubleshooting and Common Questions NI CAN User Manual B 4 www natinst com resource that caused the conflict and refer to the Microsoft Windows User s Guide for instructions on how to use the Device Manager to reserve memory resources for legacy boards After the conflict has been resolved run the NI CAN Diagnostic utility again Interrupt Resource Conflict This error occurs if the interrupt resource assigned to a CAN interface conflicts with the interrupt resources being used by other devices in the system Resource conflicts typically occur when your system contains leg
30. CAN NI CAN User Manual NI CAN User Manual August 1999 Edition Part Number 321370C 01 Worldwide Technical Support and Product Information www natinst com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 794 0100 Worldwide Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Calgary 403 274 9391 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 China 0755 3904939 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico D F 5 280 7625 Mexico Monterrey 8 357 7695 Netherlands 0348 433466 Norway 32 27 73 00 Singapore 2265886 Spain Barcelona 93 582 0251 Spain Madrid 91 640 0085 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2377 1200 United Kingdom 01635 523545 For further support information see the Technical Support Resources appendix To comment on the documentation send e mail to techpubs natinst com Copyright 1996 1999 National Instruments Corporation All rights reserved Important Information Warranty The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a peri
31. Check CRC 1 4 Acknowledgment Bit ACK 1 5 End of Frame 1 5 CAN Error Detection and Confinement 1 5 Error Detection 1 5 Error Confinement 1 6 Low Speed CAN 1 8 NI CAN Software Overview 1 9 Independent Design 1 9 Object Oriented Design 1 9 NI CAN Object Hierarchy 1 10 NI CAN Software Components 1 12 NI CAN Driver and Utilities 1 12 Firmware Image Files 1 13 Language Interface Files
32. Corporation I 3 NI CAN User Manual F firmware image files 1 13 form error 1 6 frames See CAN frames function calls checking See status of function calls checking G G language function library 2 1 GetProcAddress function 2 3 I Identifier Extension IDE field 1 4 instance definition 1 9 interactive front panel application example 4 6 to 4 8 interrupt requirements Windows 98 95 B 6 Windows NT C 3 interrupt resource conflict Windows 98 95 B 4 Windows NT C 2 ISO 11898 standard 1 1 L LabVIEW G language function library 2 1 interactive front panel application example 4 6 to 4 8 status checking 2 11 to 2 12 language interface files 1 13 M manual See documentation memory resource conflict Windows 98 95 B 3 to B 4 Windows NT C 2 methods definition 1 9 missing CAN Interfaces Windows 98 95 no National Instruments CAN Interface B 1 to B 2 not listed in NI CAN Diagnostic utility B 4 physically absent interface B 2 Windows NT NI CAN Configuration utility C 1 not listed in NI CAN Diagnostic Utility C 2 N National Instruments CAN interfaces See CAN Interfaces missing CAN Interfaces ncAction function 2 7 2 8 ncConfig function 2 8 ncCreateNotification function 2 9 3 4 NC_ERR_OLD_DATA status code 3 2 NC_ERR_OVERFLOW status code 3 2 ncGetAttribute function 3 4 ncOpenObject function 2 8 ncRead function 2 9 NC_ST_READ_AVAIL state 3 1 to 3 2 NC_ST_WRITE_SUCCESS state
33. In the Name drop down box a small X appears after each name that has already been assigned to a physical port This indication should assist you in assigning a unique name to each port in your system Specify the Configuration Attributes Use the controls in the Attributes section to specify the configuration attributes for the CAN Network Interface Object The attribute settings are associated with the physical port and thus remain the same even if you decide to change the Name of the port A control is provided for each configuration attribute of the CAN Network Interface Object Within the Attributes section you can use the Default button to initialize the attribute controls with acceptable default values If you need help with a particular control click on the question mark near the upper right corner of the dialog box then click on the control in question to view the context sensitive online help Alternately you can right click the mouse on the control and then select What s This from the pop up menu that appears Chapter 5 NI CAN Configuration Utility NI CAN User Manual 5 6 www natinst com Configure the CAN Objects Selecting the Configure CAN Objects button opens a dialog box you can use to configure the CAN Objects for the selected port Figure 5 2 shows the CAN Object Configuration dialog box for Windows 98 95 The Windows NT dialog box is similar Figure 5 2 CAN Object Configuration Dialog Box If you need help o
34. TYPE_OBJH_P ObjHandlePtr static NCTYPE_STATUS _NCFUNC_ PncCloseObject NCTYPE_OBJH ObjHandle static NCTYPE_STATUS _NCFUNC_ PncRead NCTYPE_OBJH ObjHandle NCTYPE_UINT32 DataSize NCTYPE_ANY_P DataPtr PncOpenObject NCTYPE_STATUS _NCFUNC_ NCTYPE_STRING NCTYPE_OBJH_P GetProcAddress NicanLib LPCSTR ncOpenObject PncCloseObject NCTYPE_STATUS _NCFUNC_ NCTYPE_OBJH GetProcAddress NicanLib LPCSTR ncCloseObject PncRead NCTYPE_STATUS _NCFUNC_ NCTYPE_OBJH NCTYPE_UINT32 NCTYPE_ANY_P GetProcAddress NicanLib LPCSTR ncRead If GetProcAddress fails it returns a NULL pointer The following code fragment illustrates how to verify that none of the calls to GetProcAddress failed if PncOpenObject NULL PncCloseObject NULL PncRead NULL FreeLibrary NicanLib printf GetProcAddress failed Chapter 2 Developing Your Application NI CAN User Manual 2 4 www natinst com Your application needs to de reference the pointer to access an NI CAN function as illustrated by the following code NCTYPE_STATUS status NCTYPE_OBJH MyObjh status PncOpenObject CAN0 amp MyObjh if status lt 0 printf ncOpenObject failed Before exiting your application you need to free nican dll with the following command FreeLibrary NicanLib For more information on direct entry refer to the Win32 SDK Software Development Kit online help Choosing Wh
35. ace Appendix B Windows 98 95 Troubleshooting and Common Questions National Instruments Corporation B 5 NI CAN User Manual Common Questions What do I do if my CAN hardware is listed in the Windows Device Manager with a circled X or exclamation point overlaid on it Refer to the Problem Shown in Device Manager section of this appendix for specific information about what might cause this problem If you have already completed the troubleshooting steps fill out the forms in Appendix D Customer Communication and contact National Instruments How can I determine which type of CAN hardware I have installed Run the NI CAN Configuration utility To run the utility select Start Settings Control Panel System Select the Device Manager tab in the System Properties dialog box Click on the View devices by type radio button at the top of the sheet If any CAN hardware is correctly installed a National Instruments CAN Interfaces icon appears in the list of device types Double click this icon to see a list of installed CAN hardware How can I determine which version of the NI CAN software I have installed Run the NI CAN Diagnostic utility To run the utility select the Diagnostic item under Start Programs National Instruments CAN The NI CAN Diagnostic utility displays information about the version of the NI CAN software currently installed What do I do if the NI CAN Diagnostic utility fails with an error Refer to the
36. acy boards that use resources that have not been reserved properly with the Device Manager If a resource conflict exists write down the interrupt resource that caused the conflict and refer to the Microsoft Windows User s Guide for instructions on how to use the Device Manager to reserve interrupt resources for legacy boards After the conflict has been resolved run the NI CAN Diagnostic utility again NI CAN Software Problem Encountered This error occurs if the NI CAN Diagnostic utility detects that it is unable to communicate correctly with the CAN hardware using the installed NI CAN software If you get this error shut down your computer restart it and run the NI CAN Diagnostic utility again If the problem persists try reinstalling the NI CAN software Missing CAN Interface If a National Instruments CAN interface is physically installed in your system but is not listed in the NI CAN Diagnostic utility check the Windows Device Manager to see if Windows 98 95 has detected the hardware For more information refer to the Troubleshooting Windows Device Manager Problems section earlier in this appendix CAN Hardware Problem Encountered This error occurs if the NI CAN Diagnostic utility detects a defect in the CAN hardware If you get this error write down the numeric code shown with the error and contact National Instruments Depending on the cause of the hardware failure National Instruments may need to upgrade your CAN interf
37. ained from front panel controls 2 The application calls ncOpenObject to open the CAN Network Interface Object 3 If Configure Periodic Transmit is checked the application calls ncConfig to configure the CAN Object The name of the object is obtained using the front panel arbitration ID The data length and period are also obtained from front panel controls 4 If Configure Periodic Transmit is checked the application calls ncOpenObject to open the CAN Object 5 If the WRITE button has been selected the front panel arbitration ID remote data flag data length and data are used to call ncWrite for the CAN Network Interface Object 6 The ncRead function is called for the CAN Network Interface Object to see if a CAN frame has been received If ncRead returns a code of zero success in its error out cluster the received CAN frame is inserted into the Received Frames array Chapter 4 Application Examples NI CAN User Manual 4 8 www natinst com 7 If Configure Periodic Transmit is checked the application calls ncWrite for the CAN Object to update the data used for periodic transmissions 8 If no NI CAN error has occurred and the Stop button has not been selected the application loops back to Step 5 9 The application calls ncCloseObject to close the CAN Network Interface Object then calls ncCloseObject to close the CAN Object Figure 4 3 Program Flowchart for Example 3 1 2 Open CAN Network Interface
38. amines the network to determine if a higher priority identifier is being transmitted simultaneously If an identifier collision is detected the losing device s immediately cease transmission and wait for the higher priority message to complete before automatically retrying Because the highest priority identifier continues its transmission without interruption this scheme is referred to as non destructive bitwise arbitration and CAN s identifier is often referred to as an arbitration ID This ability to resolve collisions and continue with high priority transmissions is one feature that makes CAN ideal for real time applications Chapter 1 Introduction National Instruments Corporation 1 3 NI CAN User Manual Figure 1 1 Example of CAN Arbitration CAN Frames In a CAN network the messages transferred across the network are called frames The CAN protocol supports two frame formats as defined in the Bosch version 2 0 specifications the essential difference being in the length of the arbitration ID In the standard frame format also known as 2 0A the length of the ID is 11 bits In the extended frame format also known as 2 0B the length of the ID is 29 bits The ISO 11898 specification supports only the standard frame format Figure 1 2 shows the essential fields of the standard and extended frame formats and the following sections describe each field Figure 1 2 Standard and Extended Frame Formats Start of Frame SOF
39. are skipped except for ncClose The ncClose function executes regardless of whether the incoming status is true or false This ensures that all NI CAN objects are closed properly when execution stops due to an error When a warning occurs in an NI CAN function execution proceeds normally To detect suspected warnings in your application you can write code in your Block Diagram to examine the code parameter or you can use the Probe Data tool on an Error out terminal during execution Chapter 2 Developing Your Application NI CAN User Manual 2 12 www natinst com For each NI CAN function you can find numeric values for the returned status code and qualifier in the online description of the function which you can access in the Block Diagram by selecting the function and typing lt Ctrl H gt Checking Status in C For applications written in C or C you should define a function to handle NI CAN warnings and errors When this function detects an error it closes all open objects then exits the application When this function detects a warning it can display a warning message or simply ignore the warning If the function has the following prototype void CheckStat NCTYPE_STATUS stat char msg then your application invokes it as follows if status 0 CheckStat status NI CAN error or warning For an example implementation of the CheckStat function refer to the C language examples in the NI CAN examples directory W
40. bVIEW maps to the corresponding C language NI CAN function refer to the NI CAN Programmer Reference Manual C C Language Interfaces You can use an NI CAN C language interface if your application is written in Microsoft Visual C C 2 0 or later Borland C C 5 0 or later or LabWindows CVI 4 0 or later with Microsoft C For other C C compilers you must access nican dll directly Chapter 2 Developing Your Application NI CAN User Manual 2 2 www natinst com To use a C C language interface include the nican h header file in your code then link the appropriate NI CAN language interface file with your application You can then call the NI CAN functions without any extra effort For C applications files with c extension include nican h by adding the following line to the beginning of your code include nican h For C applications files with cpp extension include nican h by adding the following lines to the beginning of your code define _cplusplus include nican h The _cplusplus define allows nican h to properly handle the transition from C to the C language NI CAN functions For Microsoft Visual C link your application with the NI CAN language interface for Microsoft C C nicanmsc lib For Borland C C 5 0 or later link your application with the NI CAN language interface for Borland C C nicanbor lib For Borland C C 4 5 you must use direct entry access for NI CAN For LabWind
41. cation Programming Interface API A collection of functions used by a user application to access hardware Within NI CAN you use API functions to make calls into the NI CAN driver arbitration ID An 11 or 29 bit ID transmitted as the first field of a CAN frame The arbitration ID determines the priority of the frame and is normally used to identify the data transmitted in the frame attribute The externally visible qualities of an object for example an instance Mary of class Human could have the attributes Sex and Age with the values Female and 31 Also known as property B b Bits bus off A CAN node goes into the bus off state when its transmit error counter increments above 255 The node does not participate in network traffic because it assumes that a defect exists that must be corrected Glossary NI CAN User Manual G 2 www natinst com C CAN Controller Area Network CAN LS See Low speed CAN CAN data frame Frame used to transmit the actual data of a CAN Object The RTR bit is clear and the data length indicates the number of data bytes in the frame CAN frame In addition to fields used for error detection correction a CAN frame consists of an arbitration ID an Identifier Extension SOF and EOF bits the RTR bit a four bit Data Length Code and zero to eight bytes of data CAN Network Interface Object Within NI CAN an object that encapsulates a CAN network interface on the host computer CAN
42. chanical drawings and helpful images of jumper settings and connector pinouts Application Notes A library with more than 100 short papers addressing specific topics such as creating and calling DLLs developing your own instrument driver software and porting applications between platforms and operating systems Appendix D Technical Support Resources NI CAN User Manual D 2 www natinst com Software Related Resources Instrument Driver Network A library with hundreds of instrument drivers for control of standalone instruments via GPIB VXI or serial interfaces You also can submit a request for a particular instrument driver if it does not already appear in the library Example Programs Database A database with numerous non shipping example programs for National Instruments programming environments You can use them to complement the example programs that are already included with National Instruments products Software Library A library with updates and patches to application software links to the latest versions of driver software for National Instruments hardware products and utility routines Worldwide Support National Instruments has offices located around the globe Many branch offices maintain a Web site to provide information on local services You can access these Web sites from www natinst com worldwide If you have trouble connecting to our Web site please contact your local National I
43. designed to illustrate basic NI CAN programming as well as specific concepts and techniques that can help you write your own applications The description of each example includes the programmer s task a program flowchart and numbered steps that correspond to the numbered blocks on the flowchart The following example programs are included with your NI CAN software obj2obj c is the C source code file for Example 1 obj2obj vi is the LabVIEW source code file for Example 1 In this example one CAN Object is used to periodically transmit data to another CAN Object simpanlz c is the C source file for Example 2 This example illustrates a simple CAN bus analyzer using the CAN Network Interface Object It also demonstrates usage of the ncCreateNotification function interact vi is the LabVIEW source code file for Example 3 In this example one CAN Network Interface Object and one CAN Object are used to transmit and receive CAN frames interactively ReadMult c is the C source file for the ncReadMult function This example shows how to use the function to retrieve CAN frames from the read queue The example can be used as the basis for building analyzer style applications to retrieve high speed incoming data for future analysis When used with the Network Interface Object this function allows more data processing time because it retrieves multiple frames in one call as opposed to the ncRead function that retrieves one
44. dominant 0 bits causes the current frame transmission to abort resulting in a subsequent retransmission A CAN device remains in the error active state as long as the transmit and receive error counters are both below 128 In a normally functioning network of CAN devices all devices are in the error active state Error Passive State If either the transmit error counter or the receive error counter increments above 127 the CAN device transitions into the error passive state A device in error passive state can still take part in communication but transmits a passive error flag when an error is detected This passive error flag sequence of recessive 1 bits generally does not abort frames transmitted by other devices Since passive error flags are not able to prevail over any activity on the bus line they are noticed only when the error passive device is transmitting a frame Thus if an error passive device detects a receive error on a frame which is received successfully by other devices the frame is not retransmitted One special rule to keep in mind is that when an error passive device detects an acknowledgment error it does not increment its transmit error counter Thus if a CAN network consists of only one device for instance if you do not connect a cable to your National Instruments CAN interface and that device attempts to transmit a frame it retransmits continuously but never goes into bus off state although it eventually reac
45. e components left installed B 6 C 4 NI CAN status format 2 10 to 2 11 code 2 10 determining severity of status table 2 10 error warning indicators severity 2 10 illustration 2 10 qualifier 2 11 no resources assigned error Windows NT C 1 non destructive bitwise arbitration 1 2 O obj2obj c source code 4 1 object hierarchy in NI CAN software 1 10 to 1 12 applying NI CAN objects figure 1 11 simple CAN device network application figure 1 10 object oriented design of NI CAN software 1 9 objects See also CAN Objects synonymous with instance 1 9 opening objects 2 8 operating system independence of NI CAN software 1 9 P port selection 5 5 problem solving See troubleshooting and common questions programming accessing NI CAN software 2 1 to 2 4 C C language interfaces 2 1 to 2 2 direct entry access 2 2 to 2 4 G language function library 2 1 Index National Instruments Corporation I 5 NI CAN User Manual application examples interactive LabVIEW front panel 4 6 to 4 8 simple CAN bus analyzer 4 4 to 4 6 using CAN Objects 4 2 to 4 4 CAN Network Interface Object using with CAN Objects 3 2 to 3 4 checking status of function calls 2 10 to 2 12 C and C 2 12 LabVIEW 2 11 to 2 12 NI CAN status format 2 10 to 2 11 code 2 10 error warning indicators severity 2 10 qualifier 2 11 choosing NI CAN objects 2 4 to 2 6 CAN Network Interface Objects 2 4 to 2 5 CAN objects 2
46. eObject Chapter 4 Application Examples NI CAN User Manual 4 4 www natinst com Figure 4 1 Program Flowchart for Example 1 Example 2 Simple CAN Bus Analyzer This example focuses on usage of the ncCreateNotification function within the C programming language It illustrates a simple CAN bus analyzer using the CAN Network Interface Object An automotive test engineer is writing a diagnostic utility for use in service bays This utility is used to diagnose problems with car models that use Yes No 1 2 3 4 5 6 7 8 9 Finished Ten Periods Configure CAN Objects Configure CAN Network Interface Objects Write Data to be Transmitted Periodically from CAN1 STD5 Wait for First Transmission to Complete Wait for Reception of Periodic Data on CAN0 STD5 Close CAN Objects Read Data from CAN0 STD5 Open CAN Objects ncConfig ncConfig ncOpenObject ncWrite ncWaitForState ncWaitForState ncRead ncCloseObject Chapter 4 Application Examples National Instruments Corporation 4 5 NI CAN User Manual CAN as their in vehicle network The utility monitors the car s CAN network traffic to test for defective devices incorrect sensor data and so on In developing the utility the test engineer wants two threads One thread receives data from the CAN network and places it into a buffer The other thread processes the data in the buffer in order to check for erroneous netwo
47. er Manual Firmware Image Files All National Instruments CAN hardware products contain an on board microprocessor This microprocessor is used so that all time critical aspects of the NI CAN software can be executed separately from your Windows application The firmware image which runs on the on board microprocessor nican nfw is loaded and executed automatically when your NI CAN application starts up Language Interface Files A documentation file readme txt contains information about the NI CAN language interface files A 32 bit C language include file nican h contains NI CAN function prototypes host data types and various predefined constants A 32 bit C language interface file nicanmsc lib is used by Microsoft C C applications to access the NI CAN DLL A 32 bit C language interface file nicanbor lib is used by Borland C C 5 0 or greater applications to access the NI CAN DLL A 32 bit C language interface file nican lib is used by LabWindows CVI applications to access the NI CAN DLL NI CAN function panels for LabWindows CVI nican fp enable you to develop a CAN application with LabWindows CVI A 32 bit G function library nican llb is used by LabVIEW applications to access the NI CAN DLL Application Examples The NI CAN software includes three sample applications For a detailed description of the sample application files refer to Chapter 4 Application Examples C
48. esource conflict B 3 missing CAN Interface B 2 B 4 NI CAN Diagnostic utility failures B 3 to B 4 NI CAN software problem encountered B 4 problem shown in Device Manager B 2 to B 3 Windows 98 95 Device Manager B 1 to B 3 Windows NT C 1 to C 4 CAN hardware problem encountered C 2 common questions C 3 to C 4 interrupt resource conflict C 2 memory resource conflict C 2 missing CAN interface C 2 missing CAN Interface in NI CAN Configuration utility C 1 NI CAN Diagnostic utility failures C 1 to C 2 NI CAN software problem encountered C 2 no resources assigned C 1 U uninstalling CAN hardware Windows 98 95 A 1 to A 2 Windows NT A 2 NI CAN software some components left installed B 6 C 4 Windows 98 95 or Windows NT A 3 to A 4 utilities See NI CAN Configuration utility NI CAN Diagnostic utility W waiting for available data 2 9 Windows 98 95 NI CAN driver and utilities 1 12 starting NI CAN Configuration utility 5 2 troubleshooting and common questions B 1 to B 6 CAN hardware problem encountered B 4 common questions B 5 to B 6 interrupt resource conflict B 4 memory resource conflict B 3 to B 4 missing CAN Interface B 2 B 4 NI CAN Diagnostic utility failures B 3 to B 4 NI CAN software problem encountered B 4 problem shown in Device Manager B 2 to B 3 uninstalling CAN hardware A 1 to A 2 CAN software A 3 to A 4 B 6 Index National Instruments Corporation I 7 NI CAN User Man
49. frame per call ReadMultNet vi and ReadMultObj vi are LabVIEW BridgeVIEW examples for using the ncReadNetMult vi and ncReadObjMult vi The primary difference between the two vis is the data cluster used to output the received data The ncReadNetMult vi use the NCTYPE_CAN_FRAME_TIMED cluster Chapter 4 Application Examples NI CAN User Manual 4 2 www natinst com and ncReadObjMult vi uses the NCTYPE_CAN_DATA_TIMED cluster SimpanlzLS c is the C source that shows the use of the NC_ATTR_LOG_COMM_ERRS attribute for low speed CAN applications InteractLS vi is the LabVIEW BridgeVIEW example that shows the ncNetAttrLS cluster that lets you set the NC_ATTR_LOG_COMM_ERRS attribute for low speed CAN applications Example 1 Using CAN Objects This example focuses on the basics of using CAN Objects An automotive test engineer is trying to test a variety of CAN devices One of the CAN devices is a speed display This display expects to receive the current speed of the vehicle in a CAN frame every 100 milliseconds so that the driver of the vehicle can be continuously updated Another CAN device is a speed sensor speedometer which measures the speed of the vehicle and transmits it in a CAN frame every 100 milliseconds To use NI CAN to test the speed display the engineer uses a CAN Object to simulate the role of the speed sensor This CAN Object is configured to transmit a simulated speed every 100 milliseconds By using the
50. g schemes Call ncGetAttribute to get the NC_ATTR_STATE attribute Call ncWaitForState to wait for one or more states to occur Use ncCreateNotification to register a callback for one or more states Use the ncGetAttribute function when you need to determine the current state of an object For example if you want to determine whether a background error has occurred for an object you can use ncGetAttribute to obtain the state and check for NC_ST_ERROR Use the ncWaitForState function when your application must wait for a specific state before proceeding For example if you call ncWrite to write a frame and your application cannot proceed until the frame is successfully transmitted you can call ncWaitForState to wait for NC_ST_WRITE_SUCCESS Use the ncCreateNotification function when your application must handle a specific state but can perform other processing while waiting for that state to occur The ncCreateNotification function registers a callback function which is invoked when the desired state occurs For example a callback function for NC_ST_READ_AVAIL can call ncRead and place the resulting data in a buffer Your application can then perform any tasks desired and process the CAN data only as needed National Instruments Corporation 4 1 NI CAN User Manual 4 Application Examples This chapter describes the sample applications provided with your NI CAN software The examples in this chapter are
51. g configurations 5 7 selecting CAN Object 5 6 specifying attributes 5 7 definition 1 2 NI CAN object hierarchy 1 10 to 1 12 opening 2 8 using 2 5 to 2 6 CAN software See NI CAN software CANopen protocol 1 9 checking status of function calls See status of function calls checking class definition 1 9 closing objects 2 9 common questions See troubleshooting and common questions communicating with CAN network starting 2 8 using objects 2 9 configuring objects See also NI CAN Configuration utility calling ncConfig function 2 8 using NI CAN Configuration utility 2 8 Controller Area Network See CAN NI CAN CRC Cyclic Redundancy Check field 1 4 CRC error 1 6 Cyclic Redundancy Check CRC field 1 4 D Data Bytes field 1 4 Data Length Code DLC field 1 4 device network independence of NI CAN software 1 9 DeviceNet protocol 1 9 direct entry access to NI CAN software 2 2 to 2 4 DLC Data Length Code field 1 4 documentation conventions used in manual ix x how to use manual set ix related documentation x drivers NI CAN 1 12 E End of Frame field 1 5 error confinement 1 6 to 1 8 bus off state 1 7 to 1 8 error active state 1 7 error passive state 1 7 error detection 1 5 to 1 6 acknowledgment error 1 6 bit error 1 6 CRC error 1 6 form error 1 6 stuff error 1 6 error warning indicators severity 2 10 to 2 11 See also NI CAN status format Index National Instruments
52. hapter 1 Introduction NI CAN User Manual 1 14 www natinst com Interaction of Software Components with Your Application Figure 1 5 shows the interaction between your application and the NI CAN software components Figure 1 5 Interaction of NI CAN Software Components nican dll User Mode Kernel Mode NI CAN Device Driver CAN Hardware nican nfw NI CAN Language Interface Your Application National Instruments Corporation 2 1 NI CAN User Manual 2 Developing Your Application This chapter explains how to develop an application program using the NI CAN functions Choosing Your Programming Method Choosing a Method to Access the NI CAN Software Applications can access the NI CAN dynamic link library nican dll either by using an NI CAN language interface or by direct entry access G Language LabVIEW Function Library For applications written in LabVIEW 4 0 or later or BridgeVIEW the NI CAN function library for G nican llb provides a LabVIEW function to access each NI CAN function easily You can add NI CAN functions and controls to your LabVIEW palettes by selecting Select Palette Set from the LabVIEW Edit menu then selecting nican_view The NI CAN functions can then be found in your LabVIEW Functions palette for placement into your diagram The NI CAN controls can be found in your LabVIEW Controls palette for placement into your front panel For a description of how each NI CAN function in La
53. he CAN Objects 5 6 Select the CAN Object 5 6 Add CAN Object Configurations 5 7 Remove CAN Object Configurations 5 7 Specify the Configuration Attributes 5 7 Exit the CAN Object Setting Dialog Box 5 8 Complete the Configuration 5 8 Appendix A Uninstalling the Hardware and Software Appendix B Windows 98 95 Troubleshooting and Common Questions Appendix C Windows NT Troubleshooting and Common Questions Appendix D Technical Support Resources Glossary Index Contents NI CAN User Manual viii www natinst com Figures Figure 1 1 Example of CAN Arbitration 1 3 Figure 1 2 Standard and Extended Frame Formats 1 3 Figure 1 3 Simple CAN Device Network Application 1 10 Figure 1 4 Applying NI CAN Objects to the Example in Figure 1 3 1 11 Figure 1 5 Interaction of NI CAN Software Components 1 14 Figure 2 1 General Program S
54. hen accessing the NI CAN code and qualifier within your application you should use the constants defined in nican h These constants have the same names as described in the NI CAN Programmer Reference Manual For example to check for a timeout you would use code such as the following if NC_STATCODE status NC_ERR_TIMEOUT printf NI CAN timeout National Instruments Corporation 3 1 NI CAN User Manual 3 NI CAN Programming Techniques This chapter describes techniques for using the NI CAN functions in your application For more detailed information about each NI CAN function refer to the NI CAN Programmer Reference Manual Using Queues To maintain an ordered history of data transfers NI CAN supports the use of queues also known as FIFO first in first out buffers The basic behavior of such queues is common to all NI CAN objects There are two basic types of NI CAN queues the read queue and the write queue NI CAN uses the read queue to store incoming network data items in the order they arrive You access the read queue using ncRead to obtain the data NI CAN uses the write queue to transmit network frames one at a time using the network interface hardware You access the write queue using ncWrite to store network data items for transmission State Transitions The NC_ST_READ_AVAIL state transitions from false to true when NI CAN places a new data item into an empty read queue and remains true until you read
55. henever it does not detect a dominant Acknowledgment Bit ACK Error Confinement To provide for error confinement each CAN device must implement a transmit error counter and a receive error counter The transmit error counter is incremented when errors are detected for transmitted frames and decremented when a frame is transmitted successfully The receive error counter is used for received frames in much the same way The error counters are increased more for errors than they are decreased for successful reception transmission This ensures that the error counters will generally increase when a certain ratio of frames roughly 1 8 encounter Chapter 1 Introduction National Instruments Corporation 1 7 NI CAN User Manual errors By maintaining the error counters in this manner the CAN protocol can generally distinguish temporary errors such as those caused by external noise from permanent failures such as a broken cable For complete information on the rules used to increment decrement the error counters refer to the CAN specification ISO 11898 With regard to error confinement each CAN device may be in one of three states error active error passive and bus off Error Active State When a CAN device is powered on it begins in the error active state A device in error active state can normally take part in communication and transmits an active error flag when an error is detected This active error flag sequence of
56. hes error passive state Bus Off State If the transmit error counter increments above 255 the CAN device transitions into the bus off state A device in the bus off state does not transmit or receive any frames and thus cannot have any influence on the Chapter 1 Introduction NI CAN User Manual 1 8 www natinst com bus The bus off state is used to disable a malfunctioning CAN device which frequently transmits invalid frames so that the device does not adversely impact other devices on the network When a CAN device has transitioned to bus off it can only be placed back into error active state with both counters reset to zero by manual intervention For sensor actuator types of devices this often involves powering the device off then on For NI CAN network interfaces communication can be started again using a function such as ncAction Low Speed CAN Low speed CAN is commonly used to control comfort devices in an automobile such as seat adjustment mirror adjustment and door locking It differs from high speed CAN in that the maximum baud rate is 125K and it utilizes CAN transceivers that offer fault tolerant capability This enables the CAN bus to keep operating even if one of the wires is cut or short circuited because it operates on relative changes in voltage and thus provides a much higher level of safety The fault tolerance feature means that communications capability is maintained even if any of the ISO11519
57. ich NI CAN Objects to Use An application written for NI CAN communicates on the network by using various objects Which NI CAN objects to use depends largely on the needs of your application The following sections discuss the objects provided by NI CAN and reasons why you might use each class of object Using CAN Network Interface Objects The CAN Network Interface Object encapsulates a physical interface to a CAN network usually a CAN port on an AT or PCI interface You use the CAN Network Interface Object to read and write complete CAN frames As a CAN frame arrives from over the network it can be placed into the read queue of the CAN Network Interface Object You can retrieve CAN frames from this read queue using the ncRead function For CAN Network Interface Objects the ncRead function provides a timestamp of when the frame was received the arbitration ID of the frame the type of frame data or remote the data length and the data bytes You can also use the CAN Network Interface Object to write CAN frames using the ncWrite function Some possible uses for the CAN Network Interface Object include the following You can use the read queue to log all CAN frames transferred across the network This log is useful when you need to view preceding CAN traffic to verify that all CAN devices are functioning properly Chapter 2 Developing Your Application National Instruments Corporation 2 5 NI CAN User Manual You ca
58. id one for the first parameter two for the second and so on If no qualifier exists this field has the value NC_QUAL_NONE 0 For descriptions of the NI CAN status codes and their qualifiers refer to the NI CAN Programmer Reference Manual Checking Status in LabVIEW For applications written in G LabVIEW status checking is basically handled automatically For all of the NI CAN functions the lower left and right terminals provide status information using LabVIEW Error Clusters LabVIEW Error Clusters are designed so that status information flows from one function to the next and function execution stops when an error occurs For more information refer to the Error Handling section in the LabVIEW Online Reference In NI CAN s implementation of Error Clusters the status parameter is set to true when an error occurs and is set to false when a warning or success occurs The code parameter of the Error Cluster contains the code and qualifier fields of the NI CAN status If the code parameter of the Error Cluster is not zero then a warning or error was detected When the status parameter is true the source parameter of the Error Cluster provides the name of the NI CAN function in which the error occurred Within your LabVIEW Block Diagram wire the Error in and Error out terminals of all NI CAN functions together in succession When an error is detected in any NI CAN function status parameter true all subsequent NI CAN functions
59. ing in network traffic extended arbitration ID A 29 bit arbitration ID Frames that use extended IDs are often referred to as CAN 2 0 Part B the specification that defines them F FCC Federal Communications Commission frame A unit of information transferred across a network from one node to another the protocol defines the meaning of the bit fields within a frame Also known as packet H hex Hexadecimal Hz Hertz I instance An abstraction of a specific real world thing for example Mary is an instance of the class Human Also known as object ISO International Standards Organization K KB Kilobytes of memory Glossary NI CAN User Manual G 4 www natinst com L local Within NI CAN anything that exists on the same host personal computer as the NI CAN driver Low speed CAN Implementation of CAN as defined in ISO 11519 M MB Megabytes of memory method An action performed on an instance to affect its behavior the externally visible code of an object Within NI CAN you use NI CAN functions to execute methods for objects Also known as service operation and action minimum interval For a given connection the minimum amount of time between subsequent attempts to transmit frames on the connection Some protocols use minimum intervals to guarantee a certain level of overall network performance multi drop A physical connection in which multiple devices communicate with one anothe
60. ions Bit error Stuff error CRC error Form error Acknowledgment error Chapter 1 Introduction NI CAN User Manual 1 6 www natinst com Bit Error During frame transmissions a CAN device monitors the bus on a bit by bit basis If the bit level monitored is different from the transmitted bit a bit error is detected This bit error check applies only to the Data Length Code Data Bytes and Cyclic Redundancy Check fields of the transmitted frame Stuff Error Whenever a transmitting device detects five consecutive bits of equal value it automatically inserts a complemented bit into the transmitted bit stream This stuff bit is automatically removed by all receiving devices The bit stuffing scheme is used to guarantee enough edges in the bit stream to maintain synchronization within a frame A stuff error occurs whenever six consecutive bits of equal value are detected on the bus CRC Error A CRC error is detected by a receiving device whenever the calculated CRC differs from the actual CRC in the frame Form Error A form error occurs when a violation of the fundamental CAN frame encoding is detected For example if a CAN device begins transmitting the Start Of Frame bit for a new frame before the End Of Frame sequence completes for a previous frame does not wait for bus idle a form error is detected Acknowledgment Error An acknowledgment error is detected by a transmitting device w
61. is configuration to simulate a device which responds to remote frames In general you use CAN Objects for data transfer for a specific arbitration ID especially when that data transfer needs to occur periodically Programming Model for NI CAN Applications The following steps demonstrate how to use the NI CAN functions in your application The steps are shown in Figure 2 1 in flowchart form Chapter 2 Developing Your Application National Instruments Corporation 2 7 NI CAN User Manual Figure 2 1 General Program Steps Using NI CAN Functions START END Communicate Using Objects Wait for Data Available ncWaitForState ncCreateNotification Read Data ncRead Write Data ncwrite and so on Configure Object Yes Are All Objects Configured No Open Object ncOpenObject Yes Are All Objects Open Start Communication ncAction No Close Object ncCloseObject Are All Objects Closed No Yes Yes Finished CAN Programming No Chapter 2 Developing Your Application NI CAN User Manual 2 8 www natinst com Step 1 Configure Objects Prior to opening the objects used in your application you must configure the objects with their initial attribute settings You can configure the objects in one of two ways You can use the NI CAN Configuration utility to define your objects and specify their configuration attributes This method is often preferable because it does not
62. is example processing the frame merely entails printing it to the screen 8 If the main thread does not detect a timeout or error it loops back to Step 7 to wait for more frames 9 If a timeout or error occurs the main thread prints it to the screen The timeout occurs if no frame is received within 30 seconds 10 The application calls ncCloseObject to close the CAN Network Interface Object Chapter 4 Application Examples NI CAN User Manual 4 6 www natinst com Figure 4 2 Program Flowchart for Example 2 Example 3 Interactive CAN Example This example provides an overview of how the features of NI CAN are used within LabVIEW It provides a LabVIEW front panel that you can use to interact with CAN devices and to learn the basic operation of NI CAN The interact vi front panel provides CAN Network Interface and Baud Rate controls which are used to specify the CAN interface to use Yes No No 1 2 3 8 10 Timeout Error Detected Open CAN Network Interface Object 7 If Frame Detected in Buffer Process It 5 4 If Frame Available Read Frame and Place It into Buffer Configure CAN Network Interface Object Yes Callback Invoked No 6 Yes Timeout Error Detected Close CAN Network Interface Object 9 Print Message for Timeout Error Create Notification Thread ncConfig ncOpenObject ncCreateNotification ncRead ncCloseObject Chapter 4 Application Exa
63. mples National Instruments Corporation 4 7 NI CAN User Manual such as CAN0 as well as the communication baud rate such as 125000 All frames received are displayed in an array of Received Frames If you want to transmit a specific frame you can enter the desired Arbitration Id Is Remote flag off means CAN data frame Data Length and Data bytes then select WRITE to transmit The interact vi front panel also supports an optional CAN Object configured as Transmit Data Periodically Before running the example select Configure Periodic Transmit to use this object and also select the Arbitration Id Data Length and Period to configure While the example is running you can use the Periodic Transmit Data control to update the data transmitted each period For more information on how to use the front panel of interact vi scroll up to the help text located above the front panel controls If you do not have a CAN device with which to experiment using interact vi but you have a two port CAN interface such as the PCI CAN 2 you can use two copies of interact vi to experiment Save a separate copy of the example such as interact2 vi then run one copy on one port such as CAN0 and the other copy on the other port such as CAN1 The following steps correspond to the program flowchart in Figure 4 3 1 The application calls ncConfig to configure the CAN Network Interface Object The name of the object and its baud rate are obt
64. n a particular control in this dialog box right click the mouse on the control and then select What s This from the pop up menu that appears Select the CAN Object Use the CAN Object list box to select the CAN Object you want to configure The list box lists all existing CAN Objects The names are the same as those used with NI CAN with the arbitration ID of the CAN Object shown in decimal format STD5 XTD12004 and so on If an alias has been assigned for a CAN Object the alias is listed after the name of the NI CAN Object Chapter 5 NI CAN Configuration Utility National Instruments Corporation 5 7 NI CAN User Manual Add CAN Object Configurations When you want to add a new CAN Object configuration click on the New button to enable the controls in the New CAN Object section Use the Arb ID control to enter the decimal arbitration ID for the new CAN Object Use the Extended check box to specify whether the arbitration ID is standard unchecked or extended checked You can use the optional Alias control in the New CAN Object section to enter a user defined alias for the CAN Object You can use this alias with calls to ncOpenObject as a substitute for the complete object name For example if you add a CAN Object with arbitration ID 5 to the port named CAN0 then enter an alias MotorSpeed you can open the name MotorSpeed instead of the complete name CAN0 STD5 For more information on user defined aliases refer to the
65. n results in better performance When a new data item arrives for a zero length queue it overwrites the previous item without indicating an overflow The NC_ST_READ_AVAIL and NC_ST_WRITE_SUCCESS states still behave as usual but you can ignore them if you want only the most recent data For example when NI CAN writes a new data item to the read buffer the NC_ST_READ_AVAIL state becomes true until the data item is read If you only want the most recent data you can ignore the NC_ST_READ_AVAIL state as well as the NC_ERR_OLD_DATA warning returned by ncRead Using the CAN Network Interface Object with CAN Objects For many applications it is desirable to use a CAN Network Interface Object in conjunction with higher level CAN Objects For example many CAN devices require a specific sequence of CAN frames to initialize for data transfer For such devices you can use the CAN Network Interface Object to transmit and receive frames required for initialization then use CAN Objects for data transfer such as transmitting a periodic request for data For more information on the different uses of NI CAN objects refer to the Choosing Which NI CAN Objects to Use section in Chapter 2 Developing Your Application Chapter 3 NI CAN Programming Techniques National Instruments Corporation 3 3 NI CAN User Manual When one or more CAN Objects are open the CAN Network Interface Object cannot receive frames which would normally be handled by the CAN
66. n use the write queue to transmit a sequence of CAN frames in quick succession This is useful for applications in which you need to simulate a specific sequence of CAN frames to verify proper device operation You can read and write CAN frames for access to configuration settings within a device Because such settings generally are not accessed during normal device operation a dedicated CAN Object is not appropriate For higher level protocols based on CAN you can use sequences of write read transactions to initialize communication with a device In these protocols specific sequences of CAN frames often need to be exchanged before you can access the data from a device In such cases you can use the CAN Network Interface Object to set up communication then use CAN Objects for actual data transfer with the device In general you use CAN Network Interface Objects for situations in which you need to transfer arbitrary CAN frames Using CAN Objects When a network frame is transmitted on a CAN based network it always begins with what is called the arbitration ID This arbitration ID is primarily used for collision resolution when more than one frame is transmitted simultaneously but you can also use it as a simple mechanism to identify data The CAN Object encapsulates a specific CAN arbitration ID and its associated data Every CAN Object is always associated with a specific CAN Network Interface Object used to identify the
67. ng Diagnostic Utility Failures section of this appendix for specific information about what might cause the NI CAN Diagnostic utility to fail If you have already completed the troubleshooting steps contact National Instruments How many CAN interfaces can I configure for use with my NI CAN software for Windows NT The NI CAN software can be configured to communicate with up to 10 CAN interfaces Are interrupts required for the NI CAN software for Windows NT Yes one interrupt per card is required How do I use an NI CAN language interface For information about using NI CAN language interfaces refer to Chapter 2 Developing Your Application How do I use NI CAN from within LabVIEW For information about using NI CAN from within LabVIEW refer to Chapter 2 Developing Your Application Appendix C Windows NT Troubleshooting and Common Questions NI CAN User Manual C 4 www natinst com Why does the uninstall program leave some components installed The uninstall program removes only items that the installation program installed If you add anything to a directory that was created by the installation program the uninstall program does not delete that directory because the directory is not empty after the uninstallation You will need to remove any remaining components yourself National Instruments Corporation D 1 NI CAN User Manual D Technical Support Resources This appendix describes the comprehensive resou
68. nowledgment it could mean that the receivers detected an error such as a CRC error the ACK bit was corrupted or there are no receivers for example only one device on the network In such cases the transmitter automatically retransmits the frame End of Frame Each frame ends with a sequence of recessive bits After the required number of recessive bits the CAN bus is idle and the next frame transmission can begin CAN Error Detection and Confinement One of the most important and useful features of CAN is its high reliability even in extremely noisy environments CAN provides a variety of mechanisms to detect errors in frames This error detection is used to retransmit the frame until it is received successfully CAN also provides an error confinement mechanism used to remove a malfunctioning device from the CAN network when a high percentage of its frames result in errors This error confinement prevents malfunctioning devices from disturbing the overall network traffic Error Detection Whenever any CAN device detects an error in a frame that device transmits a special sequence of bits called an error flag This error flag is normally detected by the device transmitting the invalid frame which then retransmits to correct the error The retransmission starts over from the start of frame and thus arbitration with other devices is again possible CAN devices detect the following errors which are described in the following sect
69. nstruments office or the source from which you purchased your National Instruments product s to obtain support For telephone support in the United States dial 512 795 8248 For telephone support outside the United States contact your local branch office Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Calgary 403 274 9391 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 China 0755 3904939 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico D F 5 280 7625 Mexico Monterrey 8 357 7695 Netherlands 0348 433466 Norway 32 27 73 00 Singapore 2265886 Spain Barcelona 93 582 0251 Spain Madrid 91 640 0085 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2377 1200 United Kingdom 01635 523545 National Instruments Corporation G 1 NI CAN User Manual Glossary Prefix Meaning Value m milli 10 3 k kilo 103 A action See method actuator A device that uses electrical mechanical or other signals to change the value of an external real world variable In the context of device networks actuators are devices that receive their primary data value from over the network examples include valves and motor starters Also known as final control element Appli
70. nterface Object contains an attribute you can use to set the baud rate that the network interface hardware uses for communication You can also use the CAN Network Interface Object to communicate on the CAN device network For example you can use the write function to transmit a CAN remote frame to the pushbutton device then use the read function to retrieve the resulting CAN data frame Because the CAN Network Interface Object provides Network Interface User Application LED Device Pushbutton Device Arbitration ID 5 Data Frame Arbitration ID 13 Data Frame Arbitration ID 13 Remote Frame CAN Network Interface Object CAN Object for Arbitration ID 5 CAN Object for Arbitration ID 13 Chapter 1 Introduction NI CAN User Manual 1 12 www natinst com direct access to the network interface the write and read functions require all information about the CAN frame to be specified including arbitration ID whether the frame is a CAN data frame or a CAN remote frame the number of data bytes and the frame data assuming a CAN data frame The CAN Object encapsulates a specific arbitration ID along with its data In addition to providing the ability to transmit and receive frames for a specific arbitration ID CAN Objects also provide various forms of background access For example you can configure a CAN Object for arbitration ID 13 the pushbutton to automatically transmit a CAN remote frame every 500 ms and to s
71. od of 90 days from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this document is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES
72. of an object and the term instance refers to a specific instance of that object The term object is generally used as a synonym for instance For example NI CAN defines a class called the CAN Network Interface Object which encapsulates any network interface port on a National Instruments CAN hardware product Specific instances of the CAN Network Interface Object are referenced with names like CAN0 and CAN1 Each instance of a particular class has attributes that define its externally visible qualities as well as methods that are used to perform actions For example each instance of the CAN Network Interface Object has an attribute for the baud rate bits per second used for communication as well as a method used to transmit CAN frames onto the network Chapter 1 Introduction NI CAN User Manual 1 10 www natinst com For more information on object oriented and CAN terminology refer to the Glossary NI CAN Object Hierarchy The basic model of the NI CAN software architecture is a hierarchical collection of objects instances each of which has attributes and methods The hierarchy shows relationships between various objects In general a given object in the hierarchy has an is used to access relationship with all objects above it in the hierarchy As an example consider a CAN device network in which the network interface of a host computer is physically connected to two devices a pushbutton and an LED as shown in Figure 1
73. om others of the same type For example the ISA PnP Serial Number is provided for the AT CAN This serial number is printed physically on the interface and you can use it to distinguish multiple AT CAN interfaces installed in the same computer Chapter 5 NI CAN Configuration Utility National Instruments Corporation 5 5 NI CAN User Manual To access online help for the NI CAN Configuration utility right click the mouse anywhere on the Settings tab and select Full Help from the pop up menu that appears Alternately you can select What s This from the pop up menu to see context sensitive help for the item you have clicked on Select the Port For two port CAN interfaces such as the AT CAN 2 a list box at the top of the Settings tab allows you to select which port to configure This port number is printed physically next to the CAN connectors on the back of the interface with Port 1 as the top port and Port 2 as the bottom port For one port CAN interfaces such as the AT CAN the list box always lists Port 1 Select the CAN Network Interface Object Name After you have selected the port to configure use the Name drop down box to select the name of the CAN Network Interface Object CAN0 CAN1 and so on Your application uses the CAN Network Interface Object name as a logical reference to the port You must assign a CAN Network Interface Object name for each port of every National Instruments CAN interface in your computer
74. on IDE The Identifier Extension bit differentiates standard frames from extended frames Because the IDE bit is dominant 0 for standard frames and recessive 1 for extended frames standard frames are always higher priority than extended frames Data Length Code DLC The Data Length Code is a 4 bit field that indicates the number of data bytes in a data frame In a remote frame the Data Length Code indicates the number of data bytes in the requested data frame Valid Data Length Codes range from zero to eight Data Bytes For data frames this field contains from 0 to 8 data bytes Remote CAN frames always contain zero data bytes Cyclic Redundancy Check CRC The 15 bit Cyclic Redundancy Check detects bit errors in frames The transmitter calculates the CRC based on the preceding bits of the frame and all receivers recalculate it for comparison If the CRC calculated by a receiver differs from the CRC in the frame the receiver detects an error Chapter 1 Introduction National Instruments Corporation 1 5 NI CAN User Manual Acknowledgment Bit ACK All receivers use the Acknowledgment Bit to acknowledge successful reception of the frame The ACK bit is transmitted recessive 1 and is overwritten as dominant 0 by all devices that receive the frame successfully The receivers acknowledge correct frames regardless of the acceptance test performed on the arbitration ID If the transmitter of the frame detects no ack
75. ons of conventional automotive wiring Bosch developed the Controller Area Network CAN in the mid 1980s Using CAN devices controllers sensors and actuators are connected on a common serial bus This network of devices can be thought of as a scaled down real time low cost version of networks used to connect personal computers Any device on a CAN network can communicate with any other device using a common pair of wires As CAN implementations increased in the automotive industry CAN was standardized internationally as ISO 11898 and CAN chips were created by major semiconductor manufacturers such as Intel Motorola and Phillips With these developments many manufacturers of industrial automation equipment began to consider CAN for usage in industrial applications Comparison of the requirements for automotive and industrial device networks showed many similarities including the transition away from dedicated signal lines low cost resistance to harsh environments and high real time capabilities Because of these similarities CAN became widely used in industrial applications such as textile machinery packaging machines and production line equipment such as photoelectric sensors and motion Chapter 1 Introduction NI CAN User Manual 1 2 www natinst com controllers By the mid 1990s CAN was specified as the basis of many industrial device networking protocols including DeviceNet CANopen and Smart Distributed System SDS
76. ows CVI your application is linked with the NI CAN language interface for LabWindows CVI nican lib This library is installed automatically based on the installed compatible compiler For detailed information on how to compile and link your NI CAN application refer to the readme txt file in the NI CAN examples directory Direct Entry Access You can directly access nican dll from any programming environment that allows you to request addresses of functions that a DLL exports To use direct entry access you must first load nican dll The following C language code fragment illustrates how to call the Win32 LoadLibrary function and check for an error include lt windows h gt include nican h HINSTANCE NicanLib NULL Chapter 2 Developing Your Application National Instruments Corporation 2 3 NI CAN User Manual NicanLib LoadLibrary nican dll if NicanLib NULL return FALSE Next your application must use the Win32 GetProcAddress function to get the addresses of the NI CAN functions your application needs to use For each NI CAN function used by your application you must define a direct entry prototype For the prototypes for each function exported by nican dll refer to the NI CAN Programmer Reference Manual The following code fragment illustrates how to get the addresses of the ncOpenObject ncCloseObject and ncRead functions static NCTYPE_STATUS _NCFUNC_ PncOpenObject NCTYPE_STRING ObjName NC
77. physical interface on which the CAN Object is located Your application can use multiple CAN Objects in conjunction with their associated CAN Network Interface Object The CAN Object provides high level access to a specific arbitration ID You can configure each CAN Object for different forms of background access For example you can configure a CAN Object to transmit a data frame every 100 milliseconds or to periodically poll for data by transmitting a remote frame and receiving the data frame response The arbitration ID direction of data transfer data length and when data transfer occurs periodic or unsolicited are all preconfigured for the CAN Object When you have configured and opened the CAN Object data transfer is handled in the background using read and write queues For example if the CAN Object periodically polls for data the NI CAN driver automatically handles the periodic transmission of remote frames and stores incoming Chapter 2 Developing Your Application NI CAN User Manual 2 6 www natinst com data in the read queue of the CAN Object for later retrieval by the ncRead function For CAN Objects that receive data frames the ncRead function provides a timestamp of when the data frame arrived and the data bytes of the frame For CAN Objects that transmit data frames the ncWrite function provides the outgoing data bytes Some possible uses for CAN Objects include the following You can configure a CAN Object to
78. r along a single cable N network interface A node s physical connection onto a network NI CAN driver Device driver and or firmware that implement all the specifics of a CAN network interface Within NI CAN this software implements the CAN Network Interface Object as well as all objects above it in the object hierarchy node A physical assembly linked to a communication line cable capable of communicating across the network according to a protocol specification Also known as device notification Within NI CAN an operating system mechanism that the NI CAN driver uses to communicate events to your application You can think of a notification of as an API function but in the opposite direction Glossary National Instruments Corporation G 5 NI CAN User Manual O object See instance object oriented A software design methodology in which classes instances attributes and methods are used to hide all of the details of a software entity that do not contribute to its essential characteristics P peer to peer Network connection in which data is transmitted from the source to its destination s without need for an explicit request Although data transfer is generally unidirectional the protocol often uses low level acknowledgments and error detection to ensure successful delivery periodic Connections that transfer data on the network at a specific rate polled Request response connection in which a reques
79. rces available to you in the Technical Support section of the National Instruments Web site and provides technical support telephone numbers for you to use if you have trouble connecting to our Web site or if you do not have internet access NI Web Support To provide you with immediate answers and solutions 24 hours a day 365 days a year National Instruments maintains extensive online technical support resources They are available to you at no cost are updated daily and can be found in the Technical Support section of our Web site at www natinst com support Online Problem Solving and Diagnostic Resources KnowledgeBase A searchable database containing thousands of frequently asked questions FAQs and their corresponding answers or solutions including special sections devoted to our newest products The database is updated daily in response to new customer experiences and feedback Troubleshooting Wizards Step by step guides lead you through common problems and answer questions about our entire product line Wizards include screen shots that illustrate the steps being described and provide detailed information ranging from simple getting started instructions to advanced topics Product Manuals A comprehensive searchable library of the latest editions of National Instruments hardware and software product manuals Hardware Reference Database A searchable database containing brief hardware descriptions me
80. require configuration to be handled within your application itself Also the NI CAN Configuration utility provides online help that describes each of the configuration attributes Each object can be configured within your application by calling the ncConfig function This function takes the name of the object to configure along with a list of configuration attribute settings Step 2 Open Objects You must call the ncOpenObject function to open each object you use within your application The ncOpenObject function returns a handle for use in all subsequent NI CAN calls for that object When you are using the G language LabVIEW function library this handle is passed through the upper left and right terminals of each NI CAN function used after the open Step 3 Start Communication You must start communication on the CAN network before you can use your objects to transfer data If you configured your CAN Network Interface Object to start on open then that object and all of its higher level CAN Objects are started automatically by the ncOpenObject function so nothing special is required for this step If you disabled the start on open attribute then when your application is ready to start communication use the CAN Network Interface Object to call the ncAction function with the Opcode parameter set to NC_OP_START This call is often useful when you want to use ncWrite to place outgoing data in write queues prior to starting comm
81. resence sensors Also known as transmitter standard arbitration ID An 11 bit arbitration ID Frames that use standard IDs are often referred to as CAN 2 0 Part A standard IDs are by far the most commonly used U unsolicited Connections that transmit data on the network sporadically based on an external event Also known as nonperiodic sporadic and event driven W watchdog timeout A timeout associated with a connection that expects to receive network data at a specific rate If data is not received before the watchdog timeout expires the connection is normally stopped You can use watchdog timeouts to verify that the remote node is still operational National Instruments Corporation I 1 NI CAN User Manual Index A Acknowledgment Bit ACK field 1 5 acknowledgment error 1 6 application development See programming application examples interactive LabVIEW front panel 4 6 to 4 8 simple CAN bus analyzer 4 4 to 4 6 using CAN Objects 4 2 to 4 4 arbitration example of CAN arbitration figure 1 3 non destructive bitwise 1 2 arbitration ID definition 1 2 using CAN Objects 2 5 to 2 6 Arbitration ID field 1 4 attributes definition 1 9 specifying configuration attributes 5 5 B bit error 1 6 bus off state 1 7 to 1 8 C C C languages accessing NI CAN software 2 1 to 2 2 status checking 2 12 CAN See also NI CAN arbitration 1 2 to 1 3 error confinement 1 7 error detection 1 5 to 1 6 histor
82. rk traffic The following steps correspond to the program flowchart in Figure 4 2 1 The application calls ncConfig to configure the CAN Network Interface Object used for bus analysis CAN0 The masks and comparators are configured such that all CAN data frames are received Normally this configuration would be handled using the NI CAN Configuration utility but ncConfig is used instead to keep the example self contained 2 The application calls ncOpenObject to open the CAN Network Interface Object 3 The application calls ncCreateNotification to create the notification thread which is used to receive frames into the buffer This is done by registering a callback function for the NC_ST_READ_AVAIL state After creating the notification thread the main thread proceeds to Step 7 4 The notification thread remains idle until its callback function is invoked by the NI CAN driver 5 If the callback function detects the NC_ST_READ_AVAIL state ncRead is called to read the frame and the frame is placed into the buffer for processing by the main thread 6 If the callback function detects a timeout or error it indicates the problem to the main thread then proceeds to Step 9 If no timeout or error is detected the callback function re enables the notification and returns to Step 4 idle 7 If the main thread detects a new frame in the buffer placed there by the notification thread in Step 5 it processes the frame For th
83. s immediately below National Instruments CAN Interfaces double click on the particular interface type you want to configure If you have only one National Instruments CAN interface in your computer only one interface type appears in the list If an exclamation point or an X appears next to the interface there is a problem and you should refer to the Problem Shown in Device Manager section of Appendix B Windows 98 95 Troubleshooting and Common Questions to resolve your problem before you continue Use the Resources tab to provide information about the hardware resources assigned to the CAN interface and use the Settings tab to configure the objects for the CAN interface For information on using the Settings tab to configure your objects refer to Configuring Objects with the NI CAN Configuration Utility later in this chapter Chapter 5 NI CAN Configuration Utility National Instruments Corporation 5 3 NI CAN User Manual Starting the NI CAN Configuration Utility in Windows NT To start the NI CAN Configuration utility on Windows NT open your Windows NT Control Panel and double click on NI CAN Configuration Because you can use the NI CAN Configuration utility to modify the configuration of the NI CAN kernel drivers you must be logged on to Windows NT as the Administrator to make any changes If you start the NI CAN Configuration utility without Administrator privileges it runs in read only mode you can view the settings but yo
84. t for data is sent to a device and the device sends back a response with the desired value protocol A formal set of conventions or rules for the exchange of information among nodes of a given network R RAM Random access memory remote Within NI CAN anything that exists in another node of the device network not on the same host as the NI CAN driver Remote Transmission Request RTR bit This bit follows the arbitration ID in a frame and indicates whether the frame is the actual data of the CAN Object CAN data frame or whether the frame is a request for the data CAN remote frame request response Network connection in which a request is transmitted to one or more destination nodes and those nodes send a response back to the requesting node In industrial applications the responding slave device is usually a sensor or actuator and the requesting master device is usually a controller Also known as master slave Glossary NI CAN User Manual G 6 www natinst com resource Hardware settings used by National Instruments CAN hardware including an interrupt request level IRQ and an 8 KB physical memory range such as D0000 to D1FFF hex S s Seconds sensor A device that measures electrical mechanical or other signals from an external real world variable in the context of device networks sensors are devices that send their primary data value onto the network examples include temperature sensors and p
85. t in the system Problem Shown in Device Manager If a CAN interface is not working properly its icon has a circled X or exclamation mark overlaid on it as shown in Figure B 1 Figure B 1 CAN Interface That Is Not Working Properly This problem can occur for several reasons If you encounter this problem the Device Manager should list an error code that indicates why the problem occurred To see the error code for a particular interface select the name of the interface and click on the Properties button to go to the General tab for that CAN interface The Device Status section of the General tab shows the error code Locate the error code in the following list to find out why your CAN interface is not working properly Code 8 The NI CAN software was incompletely installed To solve this problem reinstall the NI CAN software Code 9 Windows 98 95 had a problem reading information from the CAN interface Contact National Instruments for assistance Code 12 The CAN interface was not assigned a physical memory range If your computer does not have 8 KB of available memory Windows 98 95 might configure your CAN interface without a physical memory assignment The NI CAN software cannot function without 8 KB of physical memory Another way to verify this problem Appendix B Windows 98 95 Troubleshooting and Common Questions National Instruments Corporation B 3 NI CAN User Manual is to look at the Resource
86. t you are already familiar with the Windows system you are using How To Use the Manual Set Use the getting started manual to install and configure your CAN hardware and the NI CAN software Use this NI CAN User Manual to learn the basics of CAN and how to develop an application program The user manual also contains detailed examples Use the NI CAN Programmer Reference Manual for specific information about each NI CAN function and object such as format parameters and possible errors Conventions The following conventions appear in this manual The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes a note which alerts you to important information bold Bold text denotes items that you must select or click on in the software such as menu items and dialog box options Bold text also denotes parameter names italic Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a placeholder for a word or value that you must supply monospace Text in this font denotes text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives pa
87. talled in your system but is not listed in the NI CAN Diagnostic utility check to see if the NI CAN Configuration utility has detected the hardware For more information refer to the Missing CAN Interface in the NI CAN Configuration Utility section earlier in this appendix CAN Hardware Problem Encountered This error occurs if the NI CAN Diagnostic utility detects a defect in the CAN hardware If you get this error write down the numeric code shown with the error and contact National Instruments Depending on the cause of the hardware failure National Instruments may need to upgrade your CAN interface Appendix C Windows NT Troubleshooting and Common Questions National Instruments Corporation C 3 NI CAN User Manual Common Questions How can I determine which type of CAN hardware I have installed Run the NI CAN Configuration utility To run the utility select Start Settings Control Panel NI CAN Configuration If any CAN hardware is correctly installed it is listed under National Instruments CAN Interfaces How can I determine which version of the NI CAN software I have installed Run the NI CAN Diagnostic utility To run the utility select the Diagnostic item under Start Programs National Instruments CAN The NI CAN Diagnostic utility displays information about the version of the NI CAN software currently installed What do I do if the NI CAN Diagnostic utility fails with an error Refer to the Troubleshooti
88. teps Using NI CAN Functions 2 7 Figure 2 2 Status Format 2 10 Figure 3 1 Flowchart for CAN Frame Reception 3 3 Figure 4 1 Program Flowchart for Example 1 4 4 Figure 4 2 Program Flowchart for Example 2 4 6 Figure 4 3 Program Flowchart for Example 3 4 8 Figure 5 1 NI CAN Settings Dialog Box for an AT CAN 2 5 4 Figure 5 2 CAN Object Configuration Dialog Box 5 6 Figure A 1 Selecting an Interface to Remove from Windows 98 95 A 2 Figure A 2 Add Remove Programs Properties Dialog Box A 3 Figure A 3 NI CAN Uninstallation Results A 4 Figure B 1 CAN Interface That Is Not Working Properly B 2 Table Table 2 1 Determining Severity of Status 2 10 National Instruments Corporation ix NI CAN User Manual About This Manual This manual describes the features of the NI CAN software This manual assumes tha
89. the last data item from the queue and the queue is empty The NC_ST_WRITE_SUCCESS state transitions from false to true when the write queue is empty and NI CAN has successfully transmitted the last data item onto the network The NC_ST_WRITE_SUCCESS state remains true until you write another data item into the write queue Empty Queues For both read and write queues the behavior for reading an empty queue is similar When you read an empty queue the previous data item is returned again For example if you call ncRead when NC_ST_READ_AVAIL is false Chapter 3 NI CAN Programming Techniques NI CAN User Manual 3 2 www natinst com the data from the previous call to ncRead is returned again along with the NC_ERR_OLD_DATA warning If no data item has yet arrived for the read queue a default data item is returned which consists of all zeros You should generally wait for NC_ST_READ_AVAIL prior to the first call to ncRead Full Queues For both read and write queues the behavior for writing a full queue is similar When you write a full queue NI CAN returns the NC_ERR_OVERFLOW status codes For example if you write too many data items to a write queue the ncWrite function eventually returns the overflow error Disabling Queues If you do not need a complete history of all data items you may prefer to disable the read queue and or write queue by setting its length to zero Using zero length queues generally saves memory and ofte
90. ths directories About This Manual NI CAN User Manual x www natinst com programs subprograms subroutines device names functions operations variables filenames and extensions and code excerpts Related Documentation The following documents contain information that you may find helpful as you read this manual ANSI ISO Standard 11898 1993 Road Vehicles Interchange of Digital Information Controller Area Network CAN for High Speed Communication ANSI ISO Standard 11519 1 2 Road Vehicles Low Speed Serial Data Communications Part 1 and 2 CAN Specification Version 2 0 1991 Robert Bosch Gmbh Postfach 500 D 7000 Stuttgart 1 LabVIEW Online Reference Win32 Software Development Kit SDK online help Microsoft User s Guide National Instruments Corporation 1 1 NI CAN User Manual 1 Introduction This chapter gives an overview of CAN and the NI CAN software CAN Overview History and Usage of CAN In the past few decades the need for improvements in automotive technology has led to increased usage of electronic control systems for functions such as engine timing anti lock brake systems and distributorless ignition With conventional wiring data is exchanged in these systems using dedicated signal lines As the complexity and number of devices has increased usage of dedicated signal lines has become increasingly difficult and expensive To overcome the limitati
91. tore the data of the resulting CAN data frame for later retrieval After the CAN Object is configured in this manner you can use the read function to obtain a single data byte that holds the most recent state of the pushbutton NI CAN Software Components The following section highlights important components of the NI CAN software and describes the function of each component NI CAN Driver and Utilities A documentation file readme txt contains important information about the NI CAN software and a description of any new features Before you use the software read this file for the most recent information A 32 bit multitasking aware device driver is used to interface with National Instruments CAN hardware Under Windows 98 95 this is a dynamically loadable Plug and Play aware virtual device driver VxD Under Windows NT this is a native Windows NT kernel driver A Win32 dynamic link library nican dll acts as the interface between all CAN applications and the NI CAN device driver The NI CAN Configuration utility is used to modify the configuration of the NI CAN software Under Windows 98 95 this utility is integrated into the Windows Device Manager Under Windows NT this utility is a control panel application The NI CAN Diagnostic utility is used to verify that the CAN hardware and software have been installed properly Chapter 1 Introduction National Instruments Corporation 1 13 NI CAN Us
92. ts with the memory resources being used by other devices in the system Resource conflicts typically occur when your system contains legacy boards that use the resources you assigned using the NI CAN Configuration utility If a resource conflict exists use the Resources button in the NI CAN Configuration utility to assign a different memory resource to the CAN interface After the conflict has been resolved run the NI CAN Diagnostic utility again Interrupt Resource Conflict This error occurs if the interrupt resource assigned to a CAN interface conflicts with the interrupt resources being used by other devices in the system Resource conflicts typically occur when your system contains legacy boards that use the resources you assigned using the NI CAN Configuration utility If a resource conflict exists use the Resources button in the NI CAN Configuration utility to assign a different interrupt resource to the CAN interface After the conflict has been resolved run the NI CAN Diagnostic utility again NI CAN Software Problem Encountered This error occurs if the NI CAN Diagnostic utility detects that it is unable to communicate correctly with the CAN hardware using the installed NI CAN software If you get this error shut down your computer restart it and run the NI CAN Diagnostic utility again If the problem persists try reinstalling the NI CAN software Missing CAN Interface If a National Instruments CAN interface is physically ins
93. u cannot make changes The main dialog box of the NI CAN Configuration utility for Windows NT contains a list of all National Instruments CAN interfaces in your computer For each CAN interface the Resources button opens a dialog box you can use to specify hardware resources for the CAN interface and the Settings button opens a dialog box you can use to configure the objects for the CAN interface For information on using the Settings tab to configure your objects refer to Configuring Objects with the NI CAN Configuration Utility later in this chapter Note Because the current version of Windows NT is not fully Plug and Play you must specify valid hardware resources for the CAN interface using the Resources button before using your National Instruments CAN interface with Windows NT For information on verifying proper resource assignment refer to your NI CAN getting started manual After you have finished configuring your CAN interfaces click on the OK button to close the dialog box Chapter 5 NI CAN Configuration Utility NI CAN User Manual 5 4 www natinst com Configuring Objects with the NI CAN Configuration Utility Figure 5 1 shows the Settings dialog box for an AT CAN 2 The dialog box shown is for Windows 98 95 but the Windows NT dialog box is similar Figure 5 1 NI CAN Settings Dialog Box for an AT CAN 2 Hardware information appears at the top of the dialog box so you can differentiate the selected CAN interface fr
94. ual Windows NT NI CAN driver and utilities 1 12 starting NI CAN Configuration utility 5 3 troubleshooting and common questions C 1 to C 4 CAN hardware problem encountered C 2 common questions C 3 to C 4 interrupt resource conflict C 2 memory resource conflict C 2 missing CAN interface C 2 missing CAN Interface in NI CAN Configuration utility C 1 NI CAN Diagnostic utility failures C 1 to C 2 NI CAN software problem encountered C 2 no resources assigned C 1 uninstalling CAN hardware A 2 CAN software A 3 to A 4 C 4
95. unication If you want to reset the CAN hardware completely to clear a pending Error Passive state you can use the CAN Network Interface Object to call the ncAction function with the Opcode parameter set to NC_OP_RESET This reset must be done prior to starting communication Chapter 2 Developing Your Application National Instruments Corporation 2 9 NI CAN User Manual Step 4 Communicate Using Objects After you open your objects and start communication you are ready to transfer data on the CAN network The manner in which data is transferred depends on the configuration of the objects you are using For this example assume that you are communicating with a CAN device that periodically transmits a data frame To receive this data assume that a CAN Object is configured to watch for data frames received for its arbitration ID and store that data in its read queue Step 4a Wait for Available Data To wait for the arrival of a data frame from the device you can call ncWaitForState with the DesiredState parameter set to NC_ST_READ_AVAIL The NC_ST_READ_AVAIL state tells you that data for the CAN Object has been received from the network and placed into the object s read queue Another way to wait for the NC_ST_READ_AVAIL state is to call the ncCreateNotification function so you receive a callback when the state occurs For more information on ncWaitForState and ncCreateNotification refer to the NI CAN Programmer Reference Manual
96. ure 2 2 Figure 2 2 Status Format Error and Warning Indicators Severity The error and warning bits ensure that all NI CAN errors generate a negative status and all NI CAN warnings generate a positive status The error bit is set when a function does not perform the expected behavior resulting in a negative status The warning bit is set when the function performed as expected but a condition has arisen which may require your attention If no error or warning occurs the entire status is set to zero to indicate success Table 2 1 summarizes the behavior of NI CAN status Code The code bits indicate the primary status code used for warning or errors Table 2 1 Determining Severity of Status Status Result Negative Error Function did not perform expected behavior Zero Success Function completed successfully Positive Warning Function performed as expected but a condition arose that may require your attention 31 30 29 16 15 0 Error Warning Qualifier Code Chapter 2 Developing Your Application National Instruments Corporation 2 11 NI CAN User Manual Qualifier The qualifier bits hold a qualifier for the warning or error code It is specific to individual values for the code field and provides additional information useful for detailed debugging For example if the status code indicates an invalid function parameter the qualifier holds a number that indicates the exact parameter that is inval
97. y and usage 1 1 to 1 2 CAN frames definition 1 3 fields Acknowledgment Bit ACK 1 5 Arbitration ID 1 4 Cyclic Redundancy Check CRC 1 4 Data Bytes 1 4 Data Length Code DLC 1 4 End of Frame 1 5 essential fields figure 1 3 Identifier Extension IDE 1 4 Remote Transmit Request RTR 1 4 Start of Frame SOF 1 3 reading and writing 2 5 standard and extended formats figure 1 3 CAN hardware determining type installed Windows 98 95 B 5 Windows NT C 3 problem encountered Windows 98 95 B 5 uninstalling Windows 98 95 A 1 to A 2 Windows NT A 2 CAN identifiers 1 2 CAN Interfaces See also missing CAN Interfaces interfaces supported by NI CAN software Windows 98 95 B 5 Windows NT C 3 number of configurable interfaces Windows 98 95 B 6 Windows NT C 3 CAN Network Interface Objects 2 4 to 2 5 application examples interactive interface 4 6 to 4 8 simple CAN bus analyzer 4 4 to 4 6 Index NI CAN User Manual I 2 www natinst com communication starting 2 8 using objects 2 9 possible uses 2 4 to 2 5 selecting name in NI CAN Configuration utility 5 5 using with CAN Objects 3 2 to 3 4 flowchart for CAN frame reception 3 3 CAN Objects application examples 4 1 to 4 2 choosing NI CAN objects 2 4 to 2 6 CAN Network Interface Objects 2 4 to 2 5 CAN objects 2 5 to 2 6 closing 2 9 configuration 5 6 to 5 8 adding configurations 5 7 exiting CAN Object dialog box 5 8 methods for 2 9 removin
98. you are looking for is not listed there refer to the Missing CAN Interface section of this appendix If the CAN interface you are looking for is listed but has a circled X or exclamation mark over its icon refer to the Problem Shown in Device Manager section of this appendix No National Instruments CAN Interfaces If you are certain you have a Plug and Play CAN interface installed but no National Instruments CAN Interfaces item appears in the Device Manager the interface is probably incorrectly listed under Other Devices Double click on the Other Devices item in the Device Manager and one by one remove each National Instruments CAN interface listed there by selecting its name and then clicking the Remove button After all of the Appendix B Windows 98 95 Troubleshooting and Common Questions NI CAN User Manual B 2 www natinst com National Instruments CAN interfaces have been removed from Other Devices click the Refresh button At this point the system rescans the installed hardware and the CAN interface should show up under National Instruments CAN Interfaces without any problems If the problem persists contact National Instruments Missing CAN Interface If the National Instruments CAN Interfaces item exists but the CAN interface you are looking for is not listed there the CAN interface is not properly installed For National Instruments CAN hardware this problem indicates that the interface is not physically presen

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