CAN Glossary
Control Area Networking
Dave Funk, Consultant, PHYTEC America – 06/17/1999
Terms - Alphabetized
- Acknowledge
- A single bit, transmitted by the receiving node, in response to data
- Active Error Detection
- Detected errors are made public.
- Arbitration
- Priority bitwise "Bid for Buss" to avoid collision
- Basic-CAN
- Basic functions limitations - low baud rates
- Bit-Construction
- Data bits, constructed of 8-12 Time Quantum's ("TQ")
- Bit-Monitoring
- All nodes monitor the dominate and recessive states
- Bit-Stuffing
- After 5 consecutive identical data bits, an alternate bit is imposed
- Bus Speeds
- Class A-up to 10Kb, B-10Kb to 125Kb, C-125Kb to 1 Mb
- CAN
- Controller Area Network
- A multi-master bus, using open linear structure, with one logic bus line and equal nodes
- (Complies with the 7-layer ISO/OSI communication reference model)
- CAN_H
- CAN High (+3.5V)
- CAN_L
- CAN Low (+1.5V)
- CAN_Open
- CAL Based Profile-Layer-Protocol by CiA for interchangeability
- Can Overload-Frame
- Generated by a node that is not ready
- CAN Protocol Versions
- V2.0A (Standard) and V2.0B Active and Passive (Extended)
- CiA
- CAN in Automation
- CRC
- Cyclic Redundancy Check (X15+X14+X10+X8+X7+X4+X3
- DBT
- Distributor
- DCF
- Device Description File
- Delimiter
- A passive bit between Fields
- De-Stuffing
- The action of the receiver to remove stuffing bits from the data stream.
- Device Limitation
- Maximum number of "Nodes"
- Distance Limitation
- 130 ft (40 meters)
- DLC
- Data Length Code
- DLL
- Data Link Layer (not Dynamic Link Library)
- DOD
- Device Object Directory
- Dominant Level (Bit)
- +1.5V ( bus state for a single-line) [ "Wired-And" Pull-Down]
- Dominant Bit ( Bus State)
- When the CAN_H line and the CAN_L lines are both at +2.5V
- EDS
- Electronic Data Sheet
- EMI
- Electro-Magnetic-Interference
- Error Active State
- Node will transmit a public dominantError Frame
- Error Frame
- A series of consecutive dominant or recessive bits, followed by a series of 6 recessive bits.
- Error Off State
- Error Passive State
- Node will transmit a recessive Error Frame
- Full-CAN
- Greater hardware management – higher baud rates
- Hamming
- The process of shifting & combining bits to create a unique code
- Hard Synchronization
- Synchronization on the falling edge of the Start Of Frame Bit
- ISO
- International Standardization Organization
- Line-Termination
- 120 ohms (each end of the line)
- LLC
- Logic Link Control
- MAC
- Medium Access Control
- MDTP
- Multiplexed Domain Transfer Protocol
- NMT
- Network Management
- Node
- Passive or Active Device
- Node Guarding
- Device Failure Detection ("disconnected")
- NRZ Bit Coding
- Non-Return to Zero
- OSI
- Organization of Standards Institute (7 Layer)
- Passive Error Detection
- PDO
- Process Data Object
- Phase Buffer Segment 1
- Compensation for phasing errors, by lengthening the data-bit for re-sync
- Phase Buffer Segment 2
- Compensation for phasing errors, by shortening the data-bit for re-sync
- Propagation Segment
- A programmable 1-8 Time Quanta variation (delay compensation).
- Protocol
- Established method or procedure for data communication.
- Recessive Level (Bit)
- +3.5V ( bus state for a single-line, with ground reference)
- Recessive Bit ( Bus State)
- When the CAN_H line is at +3.5V, and the CAN_L is at +1.5V
- Re-synchronizing (Hard)
- At each Recessive to Dominant edge transition
- Resynchronization Jump Width
- Limited to 1-4 TQ, but not longer than Phase Buffer Seg 2
- RTR
- Remote Transmission Request bit
- SAE
- Society of Automotive Engineers
- SDO
- Service Data Object (provide access to entries in a Device Object Directory)
- SEP
- Stored Event Protocol
- SDO
- Service Data Object
- SLIO
- Serial Link I/O (CAN slaves)
- SOF
- Start of Frame
- Sync Sync
- Pulse, or Synchronization Process
- Synchronization Segment
- The first segment within a CAN bit
- TQ
- Time Quantum /8 to /25 per Bit , [4 Segments per bit time]
- Transfer Rates
- 1 Mb/sec
- VAN
- Vehicle Area Network
Usage Terms (by groups)
- Arbitration Priority bitwise"Bid for Bus" to avoid collision
- Basic-CAN Basic functions limitations - low baud rates
- Full-CAN Greater hardware management – higher baud rates
- NRZ Bit Coding Non-Return to Zero
- Bit-Stuffing After 5 consecutive identical data bits
- Recessive Level (Bit) +3.5V ( bus state)
- Dominant Level (Bit) +1.5V ( bus state) [ "Wired-And" ]
- Line-Termination 120 ohms (each end of the line)
- Re-synchronizing (Hard) At each Recessive to Dominant edge transition
- Node Passive or Active Device
- Node Guarding Device Failure Detection
- Transfer Rates 1 Mb/sec
- Distance Limitation 130 ft (40 meters)
- Bus Speeds Class A-up to 10Kb, B-10Kb to 125Kb, C-125Kb to 1 Mb
- Device Limitation Maximum number of "Nodes"
Phases
- Standard Protocol (V2.0A)
- Extended Protocol (V2.0B)
- Passive
- Active
Key Phrases
- Bit-Stuffing After 5 consecutive identical data bits
- Node Guarding Device Failure Detection
- Re-synchronizing (Hard) At each Recessive Bit to Dominant Bit
- Noise Immunity to EMI Differential-Mode Interfacing
- Hamming The process for combining bitwise codes for uniqueness
Equipment Variations
- CANopen CAL Based Profile-Layer-Protocol by CiA for interchangeability
- CANopen Chip Micro-Controller Chip that conforms to CAN open
- CANopen Software Software Protocol that conforms to CAN Open
- CANadapter
- pcNET-CAN 8-Bit PC ISA Card, for CAN Activity
- PCAN-Dongle
- SLIOmodul Serial Link I/O Module
Frame Formats
- Data Frame
- Remote Frame
- Error Frame
- Overload Frame
- Space (Inter Frame)
Fields within the Data Frame
- Start-of-Frame 1 bit
- Arbitration Field 11 + 1 bits
- Control Field 11 + 4 bits
- Data Field 0 to 64 (plus filler bits)
- CRC Field 15 + 1 bits
- Acknowledge Field 2 bits
- End-of-Frame 7 bits
Fields within the Remote Frame
Start of Frame
- Arbitration Field 11 bits, plus Dominant RTR Bit
- Control Field 11 + 4 bits
- No Data Field
- CRC Field 15 + 1 bits
- Acknowledge Field 2 bits
- End-of-Frame
Fields within the Error Frame
- Error Flag Field 6 to 12 bits
- Error Delimiter Field 8 bits (Recessive)
Detected Errors:
- CRC Error
- ACK Error
- Form Error
- Bit Error
- Stuff Error
Fields within the Overload Frame
- Error Flag Field 6 bits
- Superimposition of Active Overload Flags 0 to 6 bits
- Error Delimiter Field 8 bits (Recessive)
Fields within the Interframe Space
- Intermission Field 3 bits
- Bus Idle (Recessive)