Baumer GNAMG - Manual (Page 7)

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3.3. CANopen communication
3.3.1. Communication profile
Communication between network users and master (PC / control) is effected by object directories and objects.
Adressing the objects is by help of a 16bit index. The individual communication objects are standardized by
CANopen communication profile DS 301. They are subdivided into several groups:
• Process DataOobjects PDO for process data transmission in realtime
• Service Data Objects SDO for write and read access to the object directory
• objects for synchronisation and error warnings of CAN users:
SYNC-object (synchronisation object) for synchronisation of network users
EMCY-object (emergency object) for error warnings of a single device or its periphery
• Network Management NMT (network management) for initialization and network control
• Layer Setting Services LSS for configuration by serial number, revision number etc within the existing
network
3.3.2. CANopen message structure
First part of the message is the COB-ID (identifier).
Structure of the 11-Bit COB-ID :
Function Code Node-ID
4 Bit Function code 7 Bit Node-ID
The function code is defining the kind of message and priority. The lower the COB-ID, the higher the priority of
the message.
Broadcast messages:
Function code COB-ID
NMT 0
SYNC 80h
Peer to Peer messages:
Function code COB-ID
Emergency 80h + Node-ID
PDO1 (tx)
1)
180h + Node-ID
PDO2 (tx)
1)
280h + Node-ID
SDO (tx)
1)
580h + Node-ID
SDO (rx)
1)
600h + Node-ID
Heartbeat 700h + Node-ID
LSS (tx)
1)
7E4h
LSS (rx)
1)
7E5h 1): (tx) and (rx) from the inclination sensor ’s point of
view
The Node-ID is optionally set anywhere between 1 and 127 via the CANopen bus (if rotary switch = 0). Default
setting of the inclination sensor is Node ID 1.
Changing the Node-ID is effected by using service data object 2101h or by LSS.
A CAN telegram consists of the COB-ID and a data packet of max. 8 bytes:
COB-ID DLC Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
Xxx x xx xx xx xx xx xx xx xx
More detailed information on the telegram structure in later chapters.