Manual VIPA System 100V
Chapter 2 Decentral block periphery CAN-Bus CANopen
HB100E - SM-CAN - Rev. 15/02
2-19
Message structure
All CANopen messages have got the following structure:
Identifier
Byte
Bit 7 ... Bit 0
1
Bit 3 ... Bit 0: most significant 4 bits of the module-ID
Bit 7 ... Bit 4: CANopen function code
2
Bit 3 ... Bit 0: data length code (DLC)
Bit 4: RTR-Bit: 0: no data (request code)
1:
data
available
Bit 7 ... Bit 5: Least significant 3 bits of the module-ID
Data
Byte
Bit 7 ... Bit 0
3 ... 10 Data
An additional division of the 2Byte identifier into function portion and a
module-ID gives the difference between this and a level 2 message. The
function determines the type of message (object) and the module-ID
addresses the receiver.
CANopen devices exchange data in the form of objects. The CANopen
communication profile defines two different object types as well as a
number of special objects.
The VIPA CAN bus coupler supports the following objects:
•
1 Transmit-PDO
•
1 Receive-PDO
•
2 SDOs
•
1 Emergency Object
•
1 Network management object NMT
•
Node Guarding
•
Heartbeat
Every object is associated with a function code. You can obtain the
required function code from the following table!
