Service Data Objects (Sdo) - ABB NCAN-02 Installation And Startup Manual

Chapter 6 – Communication
Service Data Objects
(SDO)
6-12
Service Data Objects are mainly used for transferring non-time-critical
data, e.g. parameter values. SDOs provide access to the entries in the
device Object Dictionary.
If 4 bytes or less data is to be transmitted, an 'expedited' SDO
message can be used. Larger quantities of data can be segmented, i.e.
split between several CAN messages.
The COB IDs for SDO communication are:
• Master to Slave: 600h + Node ID
• Slave to Master: 580h + Node ID.
Read:
Master to Slave
Header
1
1100xxxxxxx01000 Command
xxxxxxx = Node ID
Write:
Master to Slave ('Expedited' message with max. 4 bytes of data)
Header
1
1100xxxxxxx01000 Command
Master to Slave (Segmented message with over 4 bytes of data)
1st Frame
Header
1
1100xxxxxxx01000 Command
All Subsequent Frames
Header
1
1100xxxxxxx01000 Command
Byte
2 3 4 5
Sub-
Object Index
index
Byte
2 3 4 5
Sub-
Object Index
index
Byte
2 3 4 5
Sub-
Object Index
index
Byte
2 3 4 5
Data
NCAN-02 Installation and Start-up Guide
6 7 8
Reserved
6 7 8
Data
6 7 8
Length
6 7 8