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Appendix E CANopen Function |
E-6 Revision June 2008, 04EE, SW--PW V1.11/CTL V2.11
Initializing Pre-Operational Operational Stopped
PDO
○
SDO
○ ○
SYNC
○ ○
Time Stamp
○ ○
EMERG
○ ○
Boot-up
○
NMT
○ ○ ○
NMT Protocol is shown as follows:
NMT Master
Request
request
CS Node-ID
COB-ID=0
Start Remote Node
NMT Slave(s)
Indication
byte 0 byte 1
Indication
Indication
Indication(s)
Cs
Value Definition
1 Start
2 Stop
128 Enter Pre-Operational
129 Reset Node
130 Reset Communication
E.1.4.2 SDO (Service Data Object)
SDO is used to access the Object Dictionary in every CANopen node by Client/Server model.
One SDO has two COB-ID (request SDO and response SDO) to upload or download data
between two nodes. No data limit for SDOs to transfer data. But it needs to transfer by
segment when data exceeds 4 bytes with an end signal in the last segment.
The Object Dictionary (OD) is a group of objects in CANopen node. Every node has an OD
in the system, and OD contains all parameters describing the device and its network
behavior. The access path of OD is the index and sub-index, each object has a unique index
in OD, and has sub-index if necessary.
The request and response frame structure of SDO communication is shown as follows: