The CAN Data Telegram
Communication via the CAN bus consists of the transmission of data telegrams. Reference data, data for network
management, and data used to save data are sent with a CAN data telegram. There must be at least 3 recessive bits
between two telegrams (data frame or remote frame).
Principle Design of a CAN Data Telegram
Network Installation
When a network is installed, correct terminals on the bus lines are essential. Connect a terminating resistor of 120
ohm, 1/4 W power dissipation to both ends of the bus line between CAN_H and CAN_L (pin 2 and pin 7 of the CAN
cable). See the following diagram.
Terminator:
120 Ω, 1/4 W
Terminator:
120 Ω, 1/4 W
Node N
(submaster n)
Node 1
(submaster 1)
Sender sends a recessive
level in ACK slot; receiver
sends by errorless reception
(i.e., correct cRC) dominant
level
Recessive
Dominant
End of frame
Data field
Data safe field
(15 bit CRC; 1 bit delimiter
Validation field
(1 bit ACK slot; 1 bit ACK delimiter
Control field
Arbitration field
Start of frame
Length of
the fields
in bits
Telegram clearance
Data frame
Standard 12
Extended 32
Telegram clearance or
overload frame
Data Communication via CAN Bus (continued)
PICO Controller 2+2-XCH-V2
20
www.nordsonefd.com [email protected]
+1-401-431-7000 Sales and service of Nordson EFD dispensing systems are available worldwide.