1. CAN bus signal monitoring using the DL850V
Yokogawa Meters & Instruments Corporation

2. Leading-edge Technologies
What is CAN?
Controller Area Network Developed by BOSCH in It is a de facto standard protocol, being used for communication between ECUs in a vehicle.
It is used for data communication such as speed, RPM, break status, diagnosis information.
It is widely being used for not only for vehicle but also power, vessel, railroad, medical equipment, FA, elevator, etc.
Master
Slave
Serial communication
Leading-edge Technologies

3. Leading-edge Technologies
Merit of using CAN
Cutting Harness………low-cost, simple-design
Cutting weight………..more economical
Differential signal……noise reduction (safety)
Error detection……….higher reliability
Wire Harness
Using CAN
Simple
Light weight
complicated
Leading-edge Technologies

4. Leading-edge Technologies
(Reference) Example of in-vehicle network
For Multi-Media
For Fault-diagnosis (controlled legally)
Fault-diagnosis “CAN”
diagnosis tool
Sub-Network
For Power Train Chassis
MD/CD changer
Lamp
Instrument panel
Keyless
Door
Switch
Sensor
Squibb
Air-bag Control
For Safety
For Body Control
Gateway
Tire Pressure
Engine
Steering
The source: Renesas Electronics Corporation (Japan)
Leading-edge Technologies

5. Leading-edge Technologies
(Reference) CAN regulation
Both datalink layer and Physical layer are defined.
Application Layer
Data Link Layer (ISO11898, ISO )
Acceptance, Filtering (1:1, 1:n communication) Overload (not ready yet) Notice Resend when an error is occurred
Presentation Layer
LLC
Session Layer
Processed by CAN controller
Frame Generation (Data, Remote, Error, Overload frame) Bus monitoring, Error detection and notice Acknowledgement Arbitration
Transport Layer
MAC
Network Layer
Data Link Layer
Physical Layer (ISO11898, ISO )
Physical Layer
Bit, Timing, Synchronization, Resynchronization, Communication speed
Processed by CAN Transceiver
Bus characteristic, Driver, etc.
Controlled by Software
Controlled by Hardware
OSI basic reference model
In addition to ISO-defined standards, there are some other CAN-regulated standards such as SAE J2284, J2411.
Leading-edge Technologies

6. Leading-edge Technologies
CAN bus and Node(s)
ECU
CAN bus = Two wire
Max. 30 nodes
Leading-edge Technologies

7. Packet signal, called “FRAME”, carried and received.
Signal flow in the CAN….1
ECU
CAN bus
FRAME
Packet signal, called “FRAME”, carried and received.
Leading-edge Technologies

8. Signal flow in the CAN….2 Multi-master
ECU
CAN bus
FRAME
Each node can send a frame freely, also can receive a frame freely.
Multi-master
Leading-edge Technologies

9. Leading-edge Technologies
Features of CAN
Differential Signal
Multi-master Any node can send out a message when the bus is open.
The order of priority for sending Identifier field in a message determines the order of priority.
System flexibility Each node has no specific address, so easy for “adding” and “removing”.
Flexibility for communication speed It can be set according as a scale of network, function of system.
Advanced error handling
Excellent in error detection, notice and recovery
Data request
Any node can generate data output request for the other node.
Leading-edge Technologies

10. Leading-edge Technologies
ECU (Node) connection
Communicate via differential signal (CAN_H/CAN_L)
Max. 30 nodes can be connected.
Terminators must be placed at the end of bus line.
It is classified into two type of standards, Hi-speed CAN and Low-speed CAN. The boundary is 125kbps. The figure below shows an example of Hi-speed CAN. (Terminated by 120 ohm)
Each node is connected to CAN bus via the CAN Controller and CAN Transceiver.
CPU
CAN Controller
TX0 TX1 RX0 RX1
Transceiver
Node 1
Node 2
Node N
(max.30)
Terminator120 ohm
CAN_H ∬
Terminator120 ohm
CAN Bus Line ∬
CAN_L
Differential signal
Leading-edge Technologies

11. Leading-edge Technologies
CAN Topology
1. Bus type
The “Bus type” is typically being used.
3. Ring type
2. Star type
Leading-edge Technologies

12. Leading-edge Technologies
A variety of frames
Data Frame
　A DATA FRAME carries data from a transmitter to the receivers.
Start of Frame
Arbitration Field
Control Field
Data Field
CRC Field
ACK Field
End of Frame
The DL850V can monitor only a data frame.
Remote Frame
　A REMOTE FRAME is transmitted by a bus unit to request the transmission of the DATA FRAME with the same IDENTIFIER.
Start of Frame
Arbitration Field
Control Field
CRC Field
ACK Field
End of Frame
Error Frame
　An ERROR FRAME is transmitted by any unit on detecting a bus error.
Overload Frame An OVERLOAD FRAME is used to provide for an extra delay between the preceding and the succeeding DATA or REMOTE FRAMEs.
Leading-edge Technologies

13. Leading-edge Technologies
Data Frame format (Packet structure)
Arbitration
Control
Data
CRC
ACK
Recessive
Field
Field
SOF ID
RTR r r
DLC
0-64
EOF １
１１ Bit １ １ １ 4
(0-8 byte) 15 1 1 1 7 3
Dominant
Start of Frame: Marks the beginning of DATA FRAMES and REMOTE FRAMEs.
Identifier Field: Indicates the contents of message, also can be used for the order of priority for bus access.　Standard format:11bit／Extended format:29bit (DL850V supports both.)
RTR: Remote Transmission Request BIT. In DATA FRAMEs the RTR BIT has to be ’dominant’. Within a REMOTE FRAME the RTR BIT has to be ’recessive’.
Control Field: It includes the DATA LENGTH CODE and two bits reserved for future expansion.
Data Field: The DATA FIELD consists of the data to be transferred within a DATA FRAME. (Max. 8-byte(64-bit))
CRC Sequence & CRC Delimiter
　　　: It is the frame check sequence. The CRC SEQUENCE is followed by the CRC DELIMITER which consists of a single ’recessive’ bit.
Ack Slot & Ack Delemiter
　: All nodes having received the matching CRC SEQUENCE report this within the ACK SLOT by superscribing the ’recessive’ bit of the TRANSMITTER by a ’dominant’ bit.
End Of Frame: A flag sequence consisting of seven ’recessive’ bits.
Leading-edge Technologies

14. Leading-edge Technologies
CAN data frame and physical data
With CAN data frames, multiple data (physical data) are carried and received under a single ID.
Identifier Field
Data Field
Ex.) b
142h
0006h
2468h
0302h 1
Integrating
revolution
counter
Oil
pressure
RPM
Air cond. ON/OFF
High beam indicator
Leading-edge Technologies

15. Leading-edge Technologies
Tool lineup for CAN bus
ECU
CAN bus
FRAME
DLM2000 SB5000
CANalyzer (Vector)
WE7000
DL850V
Leading-edge Technologies

16. Mainly for CAN hardware design Mainly for CAN software design
Measurement targets of the CAN tools
Model
Target ＩＤ
ＤＡＴＡ
Mainly for CAN hardware design
Mainly for CAN software design
Leading-edge Technologies

17. Leading-edge Technologies
The difference of observed “waveform”
DLM2000, SB “waveform” = Trend of “voltage signal” of the CAN bus
DL850V “waveform” = Trend of “physical value(signal)” that is transmitted on the CAN bus
Leading-edge Technologies

18. Leading-edge Technologies
Simultaneous observation of CAN data and the analog signal(s)
CAN bus
Acceleration Sensor
ECU
ECU
Engine
ECU
Strain gauge
Transmission
Pressure sensor
Brake
thermocouple
CAN data
Analog signals
Analog Signals
DL850V
Leading-edge Technologies

19. CAN bus data monitoring
Comparison and verification of actually measured signals and CAN bus signals
You can check physical value trends of CAN bus data and the corresponding actually measured waveforms on the same screen at once.
Multi kinds of data transmitted on the CAN bus can be monitored at the same time via a single wire.
What is “CAN monitor” function?
monitoring of CAN protocol
communication data(signal) as an analog trend wafeform(s).
720240
CAN Frame
Each signal(s) can be “extracted” from a single CAN bus line.
Data
Data
E/G RPM
Vehicle speed
ECU1
ECU2
ECU3
CAN
Trend of RPM
Trend display
Trend of speed
Leading-edge Technologies

20. Leading-edge Technologies
Sampled Data and Displayed Waveforms
Extracted data is stored in memory at up to 100 ks/s while simultaneously being displayed on screen as trends.
Sampled data (trend waveform data) can be saved into files.
Leading-edge Technologies

21. Observed waveform example
You can use Vector Informatik's CANdb database file (.dbc format) to indicate the field being monitored (acquired).
CAN bus 1 frame
Pressure sensor
(analog)
CAN signal
(Physical layer)
Current
(CAN monitor waveform 1)
The timing of analog signal and CAN communication signal can be checked.
Pressure
(CAN monitor waveform 2)
Two signals transmitted by a single frame are trend-displayed as two waveforms.
Leading-edge Technologies

22. Sub channel definition
Sub channel(s) means the signal definitions of target item(s)
142h b h
2468h
0302h
CH3
CH1
CH2
Up to 16CH(Signal)/port can be defined.
(sub-CH)
Number of sub CH ID
Start bit
Bit length (Note) 1
142 32
Integrating revolution
counter 2 16
Oil pressure 3 48
RPM ：
Note: Up to 16 of bit length can be defined by module.
Leading-edge Technologies

23. Leading-edge Technologies
Sub channel definition display (Preliminary)
Signal definition setting (see the previous page)
Byte Count :Target byte length Start Bit :Position of the start bit (counted from LSB) Bit Count :Target bit length Byte Order : (Big): transmitted in “from upper byte to lower byte” order (Little): transmitted in “from lower byte to upper byte” order
Note: The bit data in a byte is transmitted by MSB first.
Port Setup (refer to the next page)
Import of setup configuration file
Factor, Offset, Unit: Scaling factor and unit for converting physical value.
Leading-edge Technologies

24. Leading-edge Technologies
Port Setup （Preliminary）
Bit Rate: Communication speed of the bus
Sample Point: Position for detecting dominant or recessive in a single bit.
Setup configuration for input port
Sync Jump Width: It can be used for correction of clock cycle in a single bit for re-synchronization.
Bit Sample Num: It can be used for designating the number of sample point(s).
Listen Only: When it turns to “ON”, any signal(Frame, Ack) is not outputted from the DL850V.
Terminator: When it turn to “ON”, the module-built-in terminator is inserted between CAN_H and CAN_L.
Leading-edge Technologies

25. Usage of CAN db database
Signal labels can be imported from CANdb database*1
Using ”Symbol Editor” free software, a message and signal can be selected(imported) from CANdb, then export as the signal labels to the DL850V.
Edits
CAN db file imports
**.dbc
Drug & Drop
Definition file for exporting to the DL850V.
*1：The CANdb file(.dbc) is a signal definition database defined by CANdb or CANdb++ presented by Vector Informatik.
**.sbl
Leading-edge Technologies

26. Leading-edge Technologies
Outputting Frame Data (Preliminary)
Single specified (defined) data frames or remote frames can be output (manually, at desired timing).
Setting the condition of frame output
A designated frame is output when “Execute” is set.
Leading-edge Technologies

27. Leading-edge Technologies
Model CAN Bus Monitor module main specifications
　　There are some competitive memory recorders which has CAN monitoring capability. However, the DL850V has a certain advantages over them such as higher sampling rate, easy for handling and costs.
Input ports: 2 (16 signals x 2 ports)
Number of Channels : 16 signals/1port
Connector type: D-sub 9 pin (male), Isolated (across port and main unit, across each port)
Supported protocols:
Physical layer: ISO (High Speed Communication)
CAN in Automation: CAN2.0B (Standard & extended message format)
Bit rates: 10 k, 20 k, 33.3 k, 50 k, 62.5 k, 66.7 k, 83.3 k, 125 k, 250 k, k, 800 k, 1 Mbps
Max. sampling rate: 100kS/s(when using 1signal/1port)
Max. 2 modules can be installed for the specified slot(s) in a single DL850V main frame.
Leading-edge Technologies