DNR-CAN-503 Product Manual - United Electronic Industries
Contents
1. 0x88200000 Fais O Copyright 2009 United Electronic Industries Inc hd Tel 508 921 4600 Date September 2009 www ueidag com Vers 3 8 File CAN 503 Chapter 2 fm 0110 0001 DNx CAN 503 Layer Chapter 2 20 Programming with the High Level API 0101 1111 1111 1111 1111 1111 make mask put a 1 where Example 2 row a has an x The others become zero 5 F F F F F convert binary to hex the acceptance mask 0x615FFFFF 29 bit filtering In this example you want to receive messages with ID s 18FEEE00 18FEF100 and OCF00400 and receive as few other messages as possible Ox18FEEEO00 1 1000 1111 1110 1110 1110 0000 0000 lay out the bits Ox18FEF100 1 1000 1111 1110 1111 0001 0000 0000 0x0CF00400 0 1100 1111 0000 0000 0100 0000 0000 B 1100 0111 1111 0111 0111 0000 0000 Oxxx shift groupings left pad 3 x s 1100 0111 1111 0111 1000 1000 0000 Oxxx gt 0110 0111 1000 0000 0010 0000 0000 0xxx i x1x0 0111 1xxx Oxxx xxxx x000 0000 Oxxx find what s common to all 3 else x 0100 0111 1000 0000 0000 0000 0000 0000 make code take common 4 x s gt 0 4 7 8 0 0 0 0 0 convert code to hex code is 0x47800000 1010 0000 0111 0111 1111 1000 0000 0111 make mask x s become 1 s else 0 A 0 7 7 F 8 0 7 convert mask to hex mask is 0xA077F807 2 3 Configuring2. The following sample code shows how to create a reader object tied to port 1 and read at most 10 frames from the CAN bus Create a reader and link it to the session s stream port 1 reader new CUeiCANReader session GetDataStream 1 read up to 10 CAN frames numFramesRead contains the number of frames actually read tUeiCANFrame frames 10 reader gt Read 10 frames amp numFramesRead 2 5 Writing Data Writing data to the CAN 503 is done using a writer object As there is no multiplexing of data contrary to what s being done with AO DO or CO Sessions you need to create one writer object per CAN port to be able to write to each port in the port list The following sample code shows how to create a writer object tied to port 2 and send one frame to the CAN bus Create a writer and link it to the session s stream port 2 writer new CUeiCANWriter session GetDataStream 2 Write 1 CAN frames tUeiCANFrame frame frame Id 0x10290 Set the arbitration Id frame IsRemote 0 This is not a remote frame frame DataSize 1 Only send 1 byte in the payload frame Data 0 0x23 Initializes the 1 byte payload writer Write 1 amp frame amp numFramesWritten 2 6 Cleaning up The session object will clean itself up when it goes out of scope or when it is the Session destroyed However you can manually clean up the session to reuse the object with a differ
3. Product Disclaimer WARNING DO NOT USE PRODUCTS SOLD BY UNITED ELECTRONIC INDUSTRIES INC AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS Products sold by United Electronic Industries Inc are not authorized for use as critical components in life support devices or systems A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness Any attempt to purchase any United Electronic Industries Inc product for that purpose is null and void and United Electronic Industries Inc accepts no liability whatsoever in contract tort or otherwise whether or not resulting from our or our employees negligence or failure to detect an improper purchase Chapter 1 Introduction n unneneneenanannnnennennna 1 1 1 Organization of this manual eeeereeeaeeeena 1 1 2 The CAN 503 Layer ia iu oo ua a torn Lola pm Res Jul a ul le 3 1 3 What is GANZ roa area ate ante i aee bed als G gece Rus iM Dad RUE DU ee ae Wel 3 1 3 1 SAd fM CPP 4 1 3 2 Functional Description oo 4 1 4 Physical 8 Data Link Communication nen 6 1 4 3 CAN Message Format rerreereereeea 7 1 4 4 Error Handling 239 eert er eed saamas pi SA ads 9 1 5 prin mm 11 1 5 5 CAN and the OSI Model Overview onee 11 1 5 6 Linking Abstraction oane
4. This chapter describes the use of low level API commands for configuring and using the CAN 503 series layer Appendix A Accessories This appendix provides a list of accessories available for CAN 503 layer s Appendix B Calibration This appendix outlines the calibration procedure for the CAN 503 series layer ndex This is an alphabetical listing of the topics covered in this manual 1 Copyright 2009 United Electronic Industries Inc Tel 508 921 4600 www ueidaq com Vers 3 8 Date September 2009 File CAN 503 Chapter 1 fm o DNx CAN 503 Layer Chapter 1 Introduction Document Conventions To help you get the most out of this manual and our products please note that we use the following conventions Tips are designed to highlight quick ways to get the job done or to reveal good ideas you might not discover on your own NOTE Notes alert you to important information CAUTION Caution advises you of precautions to take to avoid injury data loss and damage to your boards or a system crash Text formatted in bold typeface generally represents text that should be entered verbatim For instance it can represent a command as in the following example You can instruct users how to run setup using a command such as setup exe Frequently Asked Questions For frequently answered questions application notes and support visit us online at http Awww ueidaq com faq 2 Copyr
5. 13 1 5 7 Layer Capabilities eere lille 13 1 6 Wiring amp Connectors eee 15 1 7 CAN Bus wiring eee 16 Chapter 2 Programming with the High Level API 00 eneen 18 2 1 Creating a SeSSION 23 0244 see alga e Rad lu Ee n RA Gu e d e AY 18 2 2 Configuring the CAN Ports ae 18 2 2 1 Filtering CAN Messages onee 19 2 3 Configuring the Timing llis I eh 21 24 Reading Data a name oe a va M eh Ew a EVE 21 2 5 Writing Data aa ene oer exero ae aes paced Ra Edu eR pa da 22 2 6 Cleaning up the Session illii 22 Chapter 3 Programming using the Low Level API 23 Appendix eM Cru 24 In d Pc 25 Ls Copyright 2009 Tel 508 921 4600 www ueidag com Vers 3 8 hd United Electronic Industries Inc Table of Contents Date September 2009 File CAN 503 ManualTOC fm List of Figures Chapter 1 Introduction nrrnennnnnennenennennnnn nunn una 1 1 1 Photos of DNR and DNA CAN 503 Modules eee em 3 1 2 CAN and the ISO OSI Model sss seitens eintreten nennen 11 1 3 Physical and Data Link Layers and Logic Circuitry neee eenen 12 1 4 Logic Block Diagram CAN 503 Overview sse eene 12 1 5 Logic Block Diagram CAN 503 Detail sssseen men 13 1 6 CAN 503 with 4 port DNA CAN CBL Attached sss 15 1 7 Pinout Diagram for DNA CAN 503 Layer nennen ennen emen 16 1 8 CAN Nodes Connected to a C
6. Unitediclecironie Industries Ine Date September 2009 File CAN 503 ManuallX fm
7. You need to configure the CAN 503 to use the messaging timing mode the Timing Messages are equivalent to CAN frames and are represented in C with the struct tUe structure tUeiCANFrame iCanFrame uInt32 Id arbitration Id of the frame uInt32 IsRemote 1 if the frame is remote uInt32 DataSize number of bytes in the payload uInt8 Data 8 payload The CAN 503 can be programmed to wait for a certain number of messages to be received before notifying the session It is also possible to program the maximum amount of time to wait for the specified number of messages before notifying the session ras Copyright 2009 Tel 508 921 4600 www ueidaq com Vers 3 8 United Electronic Industries Inc hd Date September 2009 File CAN 503 Chapter 2 fm DNx CAN 503 Layer Chapter 2 21 Programming with the High Level API The following sample shows how to configure the messaging I O mode to be notified when 10 frames have been received or every second Ifthe CAN port receives less than 10 frames per second it will return whatever number of frames is available every second CANSession ConfigureTimingForMessagingl0 10 1 0 2 4 Reading Data Reading data from the CAN 503 is done using a reader object As there is no multiplexing of data contrary to what s being done with Al DI or CI sessions you need to create one reader object per CAN port to be able to read from each port in the port list
8. e b O i ele e e E e e e e e o 3 en aH o e e JO 2 e o e e hi e o e e m w eo e z N uM ml e o 5 Figure 1 7 Pinout Diagram for DNA CAN 503 Layer 1 7 CAN Bus As shown in Figure 1 8 the ISO11898 bus consists of two wires terminated at wiring both ends by resistors CAN devices nodes connect their CAN L and CAN H lines to the two wire CANbus A node transmits by sending the signal HIGH or LOW on CAN H and the inverse of the signal on CAN L Only the two nodes at each the end of the bus must have a terminating resistor 100 130 ohms The terminating resistors remove signal reflection at the end of the bus and balance the DC voltage levels Fus Copyright 2009 i Tel 508 921 4600 www ueidaq com Vers 3 8 b d United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 1 fm Copyright 2009 United Electronic Industries Inc DNx CAN 503 Layer Chapter 1 17 Introduction Layer Controller CAN Interface Controller optical isolation CAN Transceiver Node CAN L CAN H CAN L CAN H CAN L CAN H E Oo CANbus eo N Figure 1 8 CAN Nodes Connected to a CANbus using Standard 120 ohm Termination The bus cable length should not exceed 40m 130ft at 1Mbps or 6 7km at 10kbps due to the cable propagation delay 5nS m For cables longer than 1m 3 28 ft noise may cause timeouts when using non twisted pair cabling if you experience difficulty use twis
9. unique identifier that all nodes receive Each receiving node performs an acceptance test on the identifier to decide whether or not the message is of interest to that node If it is the message is processed If not the message is ignored The identifier also determines the importance of the message The lower the numerical value the higher the priority If two or more nodes try to transmit at the same time a non destructive arbitration function ensures that messages are sent in priority order and no messages are lost This arbitration technique is described below 1 3 2 1 Bit Types Bits are classified as either dominant or recessive The bus can have one of two complementary logical values dominant or recessive If simultaneous transmission of dominant and recessive bits occurs the resulting value will be dominant For example when using a wired AND implementation of the bus the dominant level is represented by a logical 0 and the recessive level by a logical 1 Physical states voltage light level etc that represent the logical levels are not given in this specification All nodes can listen and transmit at the same time If a node transmits a dominant bit it will see a dominant bit on the bus Also the transmitting node will not know if another node was trying to transmit If a node transmits a recessive bit however and a dominant bit is seen on the bus the node knows that someone else is on the bus 1 3 2 2 Bit En
10. ANbus using Standard 120 ohm Termination 17 Chapter2 Programming with the High Level API lesseeeeeerense 13 None Chapter3 Programming with the Low Level API llle 16 None Pat Copyright 2009 Tel 508 921 4600 www ueidag com Vers 3 8 v EEE Date September 2009 File CAN 503 ManualLOF fm Chapter 1 1 4 Organization of this manual DNx CAN 503 Layer Chapter 1 Introduction Introduction This document outlines the feature set and describes the operation of the DNx CAN 503 Controller Area Network boards The DNA version is designed for use with a PowerDNA Cube data acquisition system The DNR version is designed for use with a DNR 12 RACKtangle or a DNR 6 HalfRACK system Both versions are functionally identical This module enables communication with a Controller Area Network CAN over a CAN bus Please ensure that you have the PowerDNA Software Suite installed before attempting to run examples This DNx CAN 503 User Manual is organized as follows ntroduction This chapter provides an overview of the document content the device archi tecture connectivity and logic of the layer It also includes wiring schemes notes and specifications Programming with the High Level API This chapter provides an overview of the how to create a session configure the session for CAN bus communication and interpret results on the CAN 503 series layer Programming with the Low Level API
11. DC per channel used to power CAN transmitters CLI NIS FPGA standard logic includes input output channel list Coldfire engine etc Figure 1 5 Logic Block Diagram CAN 503 Detail The CAN 503 layer is a device that converts the electrical signal traveling along the CAN bus into raw CAN frame s For the sake of simplicity ignore the majority of electrical signaling methods described by the ISO 11898 standard and focus on the UeiDaq Framework API The UeiDag Framework API is a tool installed with the PowerDNA Software Suite that provides easy access to the CAN 503 s functionality Framework is a programming facility that allows you to connect to a cube transparently and then configure the CAN 503 to communicate with other CAN devices Attach to the CAN bus and then send and or receive CAN packets Framework sends and receives only raw CAN frames it does not generate their content Frame content is the responsibility of higher level CAN protocols e g CANopen J1939 DeviceNet SDS CAN Kingdom etc The Framework implementation is best described in an example as illustrated in Chapter 2 The controller is capable of communicating with the CAN 2 0a and CAN 2 0b protocols Controller communication speeds are software selectable between 10 and 1000kbps speed is dependent on noise and length of the cable The CAN specification recommends a maximum speed of 125k for cables up to 500m in length and a max speed of 1M
12. IS FPGA Control Logic vr 3 Q N I F Ke h T N m Electrical Isolation Figure 1 4 Logic Block Diagram CAN 503 Overview As illustrated in the diagram of Figure 1 5 the CAN bus transmits receives an electrical signal that flows through the DB 9 to DB 37 connector from to the TJA1050 CAN transceiver chip The TJA1050 CAN transceiver acts as an interface to the SJA1000 CAN interface controller it assists the SJA1000 by handling transmission reception to from the CAN bus The transceiver and controller are isolated from one another by a high speed electrical isolation IC There are four TJA1050 isolation SJA1000 structures one per port isolation is per port The SJA1000 is in turn controlled by an FPGA Control Chip which is the layer s control chip The FPGA works in conjunction with the cube s core module logic ra Copyright 2009 i Tel 508 921 4600 www ueidaq com Vers 3 8 v United Fleeronle Indusines ne Date September 2009 File CAN 503 Chapter 1 fm 4 port cable O Kai o 5 E o i 5 O D o 5 E en m o 42 o 0 c c o o N Sn e A 1 5 6 Linking Abstraction 1 5 7 Layer Capabilities Copyright 2009 United Electronic Industries Inc DNx CAN 503 Layer Chapter 1 Introduction CAN Transceivers SJA 1000 CAN Interface Controller 4x 1 per channel TJA1050 4x 1 per channel High speed 15 MHz Electrical Isolation DC
13. ZN United Electronic wy Industries The High Performance Alternative DNA DNR CAN 503 Controller Area Network Layer User Manual 4 Port Controller Area Network CAN Layer for the PowerDNA Cube and RACKtangle chassis September 2009 Edition PN Man DNx 503 0909 Version 3 8 Copyright 1998 2009 United Electronic Industries Inc All rights reserved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form by any means electronic mechanical by photocopying recording or otherwise without prior written permission Information furnished in this manual is believed to be accurate and reliable However no responsibility is assumed for its use or for any infringement of patents or other rights of third parties that may result from its use All product names listed are trademarks or trade names of their respective companies See the UEI website for complete terms and conditions of sale http www ueidaq com company terms aspx Contacting United Electronic Industries Mailing Address 27 Renmar Ave Walpole MA 02081 U S A For a list of our distributors and partners in the US and around the world please see http www ueidaq com partners Support Telephone 508 921 4600 Fax 508 668 2350 Also see the FAQs and online Live Help feature on our web site Internet Support Support support ueidag com Web Site www ueidag com FTP Site ftp ftp ueidag com
14. and will therefore not attempt to start transmission until the current message is complete The only chance for collision is between nodes that simultaneously send an SOF bit These nodes remain in step for the whole message or until all except one back off After the SOF bit is sent the arbitration field is transmitted The winning node will always have the lowest value arbitration field because it will be the first to transmit a dominant bit when other nodes are transmitting recessive bits You can therefore consider the numerical value low to high of the arbitration field to be the priority of the message Since the highest priority message is unchanged the arbitration is nondestructive In fact the node transmitting the message is not even aware that a collision occurred The only way for a node to detect a collision is for the node to observe something on the bus that is different from what it transmitted As a result the successful node and any other listening nodes never see any evidence of a collision on the bus The highest priority message is always transmitted successfully but at the expense of lower priority messages The goal is to ensure that the highest priority work is finished as soon as possible Although it is still possible to miss a hard real time deadline there should never be a situation where a high priority task misses a deadline because it was waiting for a lower priority task to run If several nodes clash one w
15. coding CAN uses NRZ non return to zero encoding with bit stuffing over a differential 2 wire bus usually twisted pair This encoding ensures compact messages with minimum transitions and high noise immunity raus Copyright 2009 i Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer Chapter1 5 Introduction 1 3 2 3 Bit Timing The ISO standard ISO 11898 specifies that each bit on the CAN bus is divided into at least 4 segments or quanta as follows e Synchronization segment Propagation segment Phase 1 segment Phase 2 segment The Sync segment always one segment long is used for synchronizing clocks A bit edge should occur within this segment whenever a data change occurs The Propagation segment compensates for any physical delays in the network Phase 1 segment is a buffer that may be shortened or lengthened to keep the clocks in sync Phase 2 segment is also a buffer that may be adjusted to compensate for negative phase errors and drift in oscillators The bit sample is always taken at the end of Phase 1 segment When any node receives a data or remote frame the receiver must sync its clock to the transmitter Hard synchronization occurs on the recessive to dominant transition of the start bit and the bit time is restarted from that edge If a bit edge does not occur during the Sync segment however resy
16. cts CAN ports 0 2 3 on device 1 at IP address 192 168 100 2 pdna 192 168 100 2 Dev1 Can0 2 3 In addition to the resource you will also configure e Port Speed Frame Format basic using an 11 bit identifier or extended using a 29 bit identifier e Port Mode normal or passive listener e Acceptance Mask used to filter incoming frames The mask selects which bits within the arbitration ID will be used for filtering Acceptance Code the arbitration ID bits selected by the acceptance mask are compared to the acceptance code and the frame is rejected if there is any difference Setting the acceptance mask to OXFFFFFFFF and the acceptance code to 0 disables filtering Zs Copyright 2009 i Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 2 fm DNx CAN 503 Layer Chapter 2 19 Programming with the High Level API Configure CAN ports 0 2 3 on device 0 session CreateCANPort pdna 192 168 100 2 Dev0 Can0 2 3 UeiCANBitsPerSecond500K Extended UeiCANPortModeNormal OxFFFFFFFF 2 2 1 Filtering CAN Messages Example 1 UeiCANFramel 0 The acceptance mask defines the bits that are relevant 0 is relevant 1 is not for comparison with the acceptance code The way you pack the bits in the mask and code depends on whether the CAN interface is configured in Basic or Extended mode and also on whether you want to f
17. d as either dominant or Control Field recessive Data length code DLC 4 Number of bytes of data 0 8 bytes Data Field Data field Oto8 Data to be transmitted length DLC field bytes CRC 15 Cyclic redundancy check CRC Field CRC delimiter 1 Must be recessive ACK slot 1 Transmitter sends recessive Any receiver ACK can assert a dominant ACK delimiter 1 Must be recessive EOF End of frame EOF 7 Must be recessive Bus Idle 1 4 4 Error Handling CAN uses several message level techniques to detect errors as follows e CRC checks Frame checks e ACKnowledgement Error Checks CAN also monitors bit levels for errors comparing actual bit levels with those transmitted If a difference is detected the transmitter flags a bit error Zs Copyright 2009 i Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 1 fm 1 4 4 1 1 4 4 2 1 4 4 3 1 4 4 4 1 4 4 5 CRC Check Frame Check ACK Check Error Frame Error Confinement Ad O Copyright 2009 United Electronic Industries Inc hd DNx CAN 503 Layer Chapter 1 10 Introduction To increase system reliability CAN implements bit stuffing Whenever a transmitter sends five consecutive bits of the same type it automatically adds a bit of opposite polarity into the message Any node receiving the message automatically removes de stuffs this added bit before processing the
18. de is the normal state of a node To be classified as Error Active the error counters must contain values less than 127 If the value in an error counter exceeds 127 the mode changes to Error Passive Mode In this mode the node can still transmit and receive messages but is constrained in how it handles errors it detects If the value in an error counter exceeds 255 the node takes itself off the bus and goes into Bus Off Mode This action removes a permanently malfunctioning babbling idiot node from the system but leaves all others on the bus unaffected This system of error handling although complex ensures very high integrity of data communication in noisy environments Tel 508 921 4600 www ueidaq com Vers 3 8 Date September 2009 File CAN 503 Chapter 1 fm 1 5 Architecture 1 5 5 CAN and the OSI Model Overview CAN based Protocol Standard DNx CAN 503 Layer Chapter 1 11 Introduction The CAN communication stack may be represented using the OSI model as shown in Figure 1 2 Application ob Es Presentation Session o Software support facilities that API Transport are not part of the OSI Model UeiDaq Framework Network Create CAN frames Driver Transceive CAN frames PowerDNA Driver Zq Logi i S gical Link Control Sq Data Link Acceptance Filtering 2 Recovery Management Media Access Control CAN 503 2 Physical A Frame Coding i CAN Contr
19. ent set of channels or parameters session CleanUp raus Copyright 2009 i Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 2 fm DNx CAN 503 Layer Chapter 3 23 Programming using the Low Level API Chapter 3 Programming using the Low Level API The low level API offers direct access to PowerDNA DagBIOS protocol and allows you to directly access device registers We recommend that you use the UeiDag Framework see Chapter 2 because it is easier to use You should only need to use the low level API if you are using an operating system other than Windows Please refer to the API Reference Manual document under Start Programs UEI PowerDNA Documentation for pre defined types error codes and functions for use with this layer ras Copyright 2009 i Tel 508 921 4600 www ueidaq com Vers 3 8 yy United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 3 fm DNx CAN 503 Layer Appendix A Accessories DNA CBL COM 1 ft long round shielded cable with 37 pin male and four 9 pin male D sub connectors Ad Copyright 2009 Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Electronic Industries Ine Date September 2009 File CAN 503 Appx fm Numerics 2 0A Format 8 2 0B Format 8 A Acceptance Mask 6 Accessories 24 ACK Check 10 Acknowledgement Error Checks 9 Arbitration Field 6 B Base F
20. for cables up to 40m The device can be operated in single scan continuous or continuous with FIFO modes The 64 byte FIFO on the SJA1000 can store up to 21 messages The controller can operate in active transmission mode passive listen only mode or self test mode The controller has built in filter circuitry to target specific messages Tel 508 921 4600 www ueidaq com Vers 3 8 Date September 2009 File CAN 503 Chapter 1 fm 13 DNx CAN 503 Layer Chapter 1 14 Introduction The TJA1050 uses an EMl resistant differential receiver to capture data from the line It can operate in listen mode where the transmitter is disabled and can send receive raw CAN data at speeds up to 1 Mbaud In the CAN 503 implementation bandwidth of 4 ports at 250k each e g 1000k total can be sustained effortlessly over a local CAN bus Also note that when powered down the TJA1050 and the CAN 503 do not disturb the bus lines Current implementation of the CAN interface on the Cube provides only register level access to the Philips SJA1000 CAN interface controllers Depending on the demand and speed requirements future implementations may include per port input and output FIFOs and full interrupt error handling in logic The CAN interface is mapped into PowerDNA address space as a set of read write registers NOTE UEISIM support of the DNx CAN 503 is limited to 300 fps input and 1000 fps output ras Copyright 2009 i Tel 508 921 4600 www ueida
21. ield Name bits Purpose Bus Idle SOF Start of Frame 1 Recessive bit Identifier A 11 First part of the unique identifier for the ere data Arbitration Field Remote Transmission Request 1 Must be recessive Discriminates between RTR a Data Frame and a request for data from a remote node Contes Two Reserved bits rO and r1 2 Reserved for future use ontro Field Data Length Code DLC 4 Number of bytes in the Data Field that follows Data Field Data field 0 to 8 Data to be transmitted length DLC field bytes CRC 15 Cyclic redundancy check CRC Field CRC delimiter 1 Must be recessive ACK slot 1 Transmitter sends recessive Any receiver ACK can override with a dominant bit ACK delimiter Must be recessive EOF End of frame EOF 7 Must be recessive INTermission Field 3 3 recessive bits INT After three INTermission periods the bus is called free Bus idle time may be any value including zero Bus Idle 1 4 3 2 2 0B Format The CAN 2 0B format uses a 29 bit identifier instead of the 11 bit identifier used by CAN 2 0A This format was developed to meet the needs of automotive applications but also to be compatible with 2 0A devices The differences between the two formats are In CAN 2 0B the arbitration field has two fields the Base ID 11 bits for compatibility with 2 0A and the Extension ID 18 bits for a combined length of 29 bits An additional bit Identifier Extension bit IDE identifies the use of
22. ight 2009 United Electronic Industries Inc Tel 508 921 4600 www ueidaq com Vers 3 8 Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer Chapter 1 3 Introduction 1 2 The CAN 503 The CAN 503 layer has the following features Layer 4independent CAN ports Bit transfer rates of 10 20 50 100 125 250 500 800 1000 kbps NOTE UEISIM support of the DNx CAN 503 is limited to 300 fps input and 1000 fps output e 24MHz base clock Completely independent bit rate settings for every port e 250V DC max isolation between ports ports and circuitry e Hot plugging support for CAN devices e nterrupt based error detection Fully compatible with ISO 11898 standard CAN 2 0a compatible 11 bit and CAN 2 0b 29 bit identifiers Message targeting and filtering e Weight of layer 120grams and core 290g in a cube 630g 22 20z DNR CAN 503 DNA CAN 503 Figure 1 1 Photos of DNR and DNA CAN 503 Modules 1 3 Whatisa A Controller Area Network CAN is a multi cast shared serial bus standard CAN designed to operate in electromagnetically noisy environments such as automotive and general industrial locations The shared serial bus is called a CAN bus Machines sensors and other devices on the CAN bus are nodes For example in a vehicle the CAN bus can control a car s dashboard displays power windows power locks windshield wipers exterior lighting and so forth Another higher speed CAN bus can contr
23. ill win out After that winning message is complete all of the non winners try again In the second round the next lowest value arbitration field wins and the process repeats There s no reason that the lowest value arbitration field can t be transmitted again however Therefore it is important to be aware that the CAN bus doesn t prevent this from happening the user must ensure that no single message type dominates the bus activity The arbitration field can be 11 or 29 bits long depending on which CAN protocol you use You can use the first few bits for priority assignment and the remaining bits to identify the type of message The CAN standard doesn t rigidly specify the meaning of those bits but the several higher level CAN compatible protocols do The CAN bus is a shared multi master event oriented message transmission bus Any node may transmit on the bus when the bus is idle multi master and communicate with any other node s that are in listening mode Nodes constantly listen to the bus and filter out messages not relevant to them as determined by the acceptance mask To determine which node of the many connected nodes may transmit on an idle bus a non destructive contention based bus arbitration scheme CSMA CD is used as described above Nodes always listen When they notice that the bus is idle they transmit their 11 or 29 bit object identifier The node with the lowest object identifier number is given priorit
24. ilter incoming frames that use 11 bit IDs or frames that use 29 bit IDs The algorithm for defining the acceptance code and mask is described in the document at http www nxp com acrobat download applicationnotes AN97076 pdf starting at page 19 ll bit filtering The following shows how to ma rejects 0x241 0x514 and Ox4i 0x241 010 0100 0001 lay out binary 0x514 101 0001 0100 0x4E1 100 1110 0001 lay out 0x541 101 0100 0001 0x641 110 0100 0001 Now shift right to make it a full reject 0100 1000 001x xxxx Y 1010 0010 100x xxxx gt 1001 1100 001x xxxx accept 1010 1000 001x xxxx De 1100 1000 001x xxxx row a 1xx0 100x Oxlx xxxx 1000 1000 0010 0000 0000 0000 0000 0000 the the bits bits to reject to accept ke a common filter configuration that El and accepts 0x541 and 0x641 convert hex to the groupings left by one place and pad with 21 x s on the 32 bit word r r XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX for each column if and at least one reject bit is different otherwise make it x then copy the accept bit 0 the acceptance code XXXX XXXX XXXX XXXX XXXX XXXX both make code XXXX XXXX XXXX XXXX XXXX XXXX accept bits are the same copy row a and make all x s be zero convert binary to hex
25. message If any receiving node detects six consecutive bits of the same polarity therefore it records a stuff error The transmitter computes a CRC code based on the content of each message it transmits and inserts it into the message frame Any receiver that accepts the message makes the same computation and compares the two results If any difference is found an error is flagged The CAN format specified that certain bit values must be present at specific locations in the message frame If a receiver sees the wrong value in any position it flags a Form or Format Error If a transmitter send a message and does not receive acknowledgment it flags an ACK Error If any node detects an error of any kind it sends an Error Frame This aborts transmission and prevents any other node from accepting the message containing the error The CAN system has a complex system of distinguishing between short term and long term errors Whenever an error is detected an error count is added to one of two error counters on each node In simplified terms receive errors are accumulated with a weighting of 1 and transmitter errors are accumulated with a weighting of 8 Conversely every good message decrements the counters accordingly with zero as a limit The values stored in each counter at any given time determine the error status of a node There are three modes of error status Error Active Error Passive and Bus Off Mode The Error Active Mo
26. nchronization is required To correct for any phase differences between transmitter and receiver oscillators the system automatically shortens or lengthens the bit time to eliminate the error The maximum number of time segments used for the adjustment is determined by a user programmable parameter called Synchronization Jump Width SJW 1 3 2 4 Reliability A CAN system can operate successfully in very severe environments It also uses a sophisticated error checking technique to ensure that all transmission errors are immediately detected In applications with speeds below 125 kbps a CAN bus will continue to operate although with higher noise if either of the two bus wires is broken if either wire is shorted to ground or if either wire is shorted to the power supply The purpose of this mode is to permit the bus to operate after a car crash has severed one of the lines Each node continues to monitor the faulty line and will resume two wire operation when the fault condition is removed 1 3 2 5 Design The fact that CAN messages are not addressed to specific nodes offers great Flexibility flexibility in designing a system Each node decides for itself whether or not the transmitted message is relevant to it As a result you can add new receiving nodes without having to make any changes to existing hardware or software Measurement information needed by several controllers can be broadcast over the bus eliminating the need for individual senso
27. ol the engine and brake system operation AN Copright2009 Tel 508 921 4600 www ueidaq com kis United Electronic Industries Inc Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer Chapter 1 Introduction 1 3 4 Standards CAN communication takes the form of the ISO OSI 7 layer model where Layers 3 to 7 application are handled by user software e g CANOpen etc Layer 2 data link is outlined by ISO 11898 1 and the CAN 2 0 specification Layer 1 physical electrical signaling and wiring is defined by ISO 11898 ISO 11898 defines the protocol for controller signaling in road vehicles e SO DIS 11898 1 Road vehicles CAN Part 1 Data link layer and physical signaling e SO DIS 11898 2 Road vehicles CAN Part 2 High speed medium access unit SO CD 11898 3 Road vehicles CAN Part 3 Low speed fault tolerant medium dependent interface SO CD 11898 4 Road vehicles CAN Part 4 Time triggered communication The ISO standards are listed for reference and theory only the CAN 503 provides transparent access directly to message frames transmitted on the CAN bus The remainder of this document refers to the ISO 11898 CAN bus and ISO 11898 CAN2 0 compliant nodes 1 3 2 Functional The data messages transmitted by any node on a CAN bus do not contain Description addresses of either the transmitting node or any receiving node The message itself contains a
28. oller Serialization deserialization SJA1000 Error Detection Physical Signaling Bit Encoding Decoding 8 Timing PMA CAN 503 Driver Receiver Characteristics OT UATOSD MO Interface CAN 503 Connectors Cable amp Connectors Cables Figure 1 2 CAN and the ISO OSI Model The physical and data link layers are implemented by the CAN 503 hardware which is detailed in the next section In concept the CAN 503 converts CAN frames into or from electrical signals Frames are retrieved from the CAN 503 by the PowerDNA driver and passed to the user application usually by facility of the UeiDaq Framework The user application is allowed the freedom and responsibility of implementing layers above data link and physical with any additional protocol you choose to use such as CANopen J1939 DeviceNet SDS CAN Kingdom proprietary or custom At the hardware level data passes at the physical level through cabling and the connector through the TJA1050 CAN transmitter receiver which is controlled by the SJA100 CAN controller Tel 508 921 4600 Date September 2009 www ueidaq com Vers 3 8 Zs Copyright 2009 United Electronic Industries Inc File CAN 503 Chapter 1 fm h 4 DNx CAN 503 Layer Chapter 1 Introduction 12 Cabling CAN Bus lt Connectors L gical LIAK Gontrol Medium Access Control 4 Physical Signaling GAN Gontroller huuumuesuu Se Cee eee eee eee see ae DB 37 Connector N
29. q com Vers 3 8 b d United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer Chapter 1 15 Introduction 1 6 Wiring 8 A DNA CAN CBL cable pictured below from the CAN 503 s 37 pin connector Connectors provides four individual 9 pin ports they are labeled by port as 1 2 3 4 with each label molded into the connector The 9 pin connectors are called stubs Port 1 Figure 1 6 CAN 503 with 4 port DNA CAN CBL Attached The following signals are located at the connector e CAN Lx Dominant Low line for port x e CAN Hx Dominant High line for port x e CAN GNDx Ground reference voltage for port x Both the CAN L and CAN H lines are protected from automotive electrical transients by ISO 7637 electrical transient transmission by capacitive and inductive coupling via lines other than supply lines in road vehicles To take advantage of noise cancellation properties use twisted pair cabling for gt 1m The B size 37 pin female D Sub connector on the CAN 503 is divided into four 9 pin D connector CAN ports by a DNA CAN CBL with the following pinouts Zs Copyright 2009 i Tel 508 921 4600 www ueidaq com Vers 3 8 b d United Flectronic Industries ne Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer Chapter 1 16 Introduction e e a 9 Le 3 Le T e e e T o e e N Oo Fir e o e a oL e e 1 N
30. rame Format 7 Bit Stuffing 10 Bit Timing 5 Bit Types 4 Block Diagram 12 Bus Arbitration 5 Bus Off Mode 10 C CAN architecture 11 bus 16 bus termination 17 communication 7 definition 3 CAN Message Format 7 CAN Nodes 17 CAN Ports 18 Collision 6 Conventions 2 CRC Check 10 CRC Checks 9 CSMA CD 5 D Data Frame 7 DNA CBL COM 24 E Error Active 10 Error Confinement 10 Error Frame 7 10 Error Handling 9 Error Passive 10 Extended Frame Format 7 Index Index Frame Checks 9 Frequently Asked Questions 2 Functional Description 4 H Hard Synchronization 5 High Level API 18 ISO 11898 4 N NRZ 4 O OSI Model 11 Overload Frame 7 P Phase 1 Segment 5 Phase 2 Segment 5 Pinout Diagram 16 Propagation Segment 5 R Reliability 5 Remote Frame 7 Resynchronization 5 S Session 18 SJA100 11 Software API Configuring 18 reading data 21 writing data 22 Standards 4 Start of Frame SOF 6 Support ii Support email support ueidaq com ii Support FTP Site ftp ftp ueidaq com ii Support Web Site www ueidag com ii Synchronization Jump Width 5 Synchronization Segment 5 F T Features 3 Terminating Resistors 16 Frame Check 10 Timing 21 Copyright 2009 Tel 508 921 4600 www ueidaq com Vers 3 8 United Electronic Industries Inc Date September 2009 File CAN 503 ManuallX fm Index TJA1050 11 W Wiring 15 cable length 13 Copyright 2009 Tel 508 921 4600 www ueidaq com Vers 3 8
31. rs for each controller 1 3 2 6 Bus To assign priority to messages CAN uses the CSMA CD method Carrier Arbitration Sense Multiple Access with Collision Detect plus a non destructive bus arbitration scheme to resolve conflicts The numerical value of each message identifier is assigned by the system designer at the start of the project This value by definition also sets the relative priority of a message The identifier with the lowest value has the highest priority Any conflicts are resolved by bitwise arbitration and a wired AND method as described previously Fais Copyright 2009 i Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Electronic Industries Ine Date September 2009 File CAN 503 Chapter 1 fm 1 4 Physical 8 Data Link Communi cation Zs Copyright 2009 b d United Electronic Industries Inc DNx CAN 503 Layer Chapter 1 Introduction A key feature of CAN bus arbitration is that the first node delays transmitting if some other node sends a dominant bit whenever the first node sends its first recessive bit Since the identifier is contained in the first part of the message transmitted all nodes except one will have delayed transmission by the time the identifier has been sent The message identifier therefore determines which messages have priority At the start of a message frame each node sends a single dominant bit called the start of frame SOF bit All listening nodes will see bus activity
32. ted pair cabling Vers 3 8 Tel 508 921 4600 www ueidaq com File CAN 503 Chapter 1 fm Date September 2009 DNx CAN 503 Layer Chapter 2 18 Programming with the High Level API Chapter2 Programming with the High Level API This section describes how to program the DNx CAN 503 using UeiDaq s Framework High Level API Since UeiDaq Framework is object oriented its objects can be manipulated in the same manner in various development environments such as Visual C Visual Basic LabVIEW or DASYLab Framework comes bundled with examples for supported programming languages They are located under the UEI programs group in Start Programs UEI Framework Examples The following subsections focus on the C API but the concept is the same regardless of programming language Please refer to the UeiDaq Framework User Manual for more information on using other programming languages 2 1 Creating a The Session object controls all operations on your PowerDNA device Session Therefore the first task is to create a session object CUeiSession session 2 2 Configuring Framework uses resource strings to select which device subsystem and the CAN Ports channels to use within a session The resource string syntax is similar to a web URL device class gt lt IP address gt lt Device Id Subsystem Channel list For PowerDNA the device class is pdna For example the following resource string sele
33. the extended format The Arbitration Field also includes a Substitute Remote Request SSR bit that ensures priority of the Standard Data Frame if both Standard and Extended Data Frames have the same 11 bit identifier e All other fields in 2 0B are the same as those in 2 0A Zs Copyright 2009 Tel 508 921 4600 www ueidaq com Vers 3 8 United Electronic Industries Inc File CAN 503 Chapter 1 fm 8 DNx CAN 503 Layer Chapter 1 9 Introduction Controllers designed for 2 0B format can transmit and receive messages in either 2 0A or 2 0B formats Controllers designed for 2 0A format are available in two types The first transmits and receives only 2 0A messages and flags an error when a 2 0B message is detected The second transmits receives and acknowledges 2 0A messages but does not process them The Extended Frame Format is structured as follows Length Description Field Name bits Purpose Bus Idle SOF Start of frame SOF 1 Recessive bit signals start of frame transmission Identifier A 11 First part of the unigue identifier for the data Substitute remote reguest SRR 1 Must be recessive Arbitration Identifier extension bit IDE 1 Must be recessive Field Identifier B 18 Second part of the unique identifier for the data Remote transmission request 1 Must be dominant RTR Reserved bits rO r1 2 Reserved bits must be set dominant but are accepte
34. y to transmit a frame and then the process repeats 6 Tel 508 921 4600 www ueidaq com Vers 3 8 Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer Chapter 1 Introduction 1 4 8 CAN Message When a device has transmission permission on the bus it broadcasts a Format message frame to the other connected devices There are four types of frames Remote Frame requests transmission of a specific identifier Error Frame transmitted by any node detecting an error e Overload Frame request to inject a delay between data remote frames Data Frame a frame that contains data Two different types of Data Frames are defined and supported by the CAN 503 Base Frame Format aka Standard CAN aka CAN 2 0A message frame These use an 11 bit identifier or 2048 possible message combinations Extended Frame Format aka Extended CAN aka CAN 2 0B message frame These frames use a larger 29 bit identifier for 512 million message combinations This mode however may not be supported in older CAN2 0A only controllers ras Copyright 2009 i Tel 508 921 4600 www ueidag com Vers 3 8 Vv United Elecironie ndusiries ine Date September 2009 File CAN 503 Chapter 1 fm DNx CAN 503 Layer h 4 Date September 2009 Chapter 1 Introduction 1 4 3 1 2 0A Format A Standard CAN Version 2 0A Message Frame has the following structure Length Description F
Download Pdf Manuals
Related Search