Object types
COMPAX CANopen
Unsigned
8
5 Object types
Each object type is determined by a Communication Object Identifier (COB-ID). This is made up of a 4 bit wide function
code which represents the object type, and the 7 bit wide device address (node ID).
Communication Object Identifier:
Function code Device address (node ID): 1...127
The value of the COB-ID specifies the priority of the object type.
The smaller the value of the COB-ID, the higher the priority of the object type.
The following table shows the preset COB-IDs:
Communi
cation
Objects:
Function
code
COB -
Identifier
(dec)
COB -
Identifier
(hex)
Defined
in Index
...
Meaning
Brodcast Objects
NMT 0000
b
0
0h
- Network management and identifier distribution
SYNC 0001
b
128
80h
1005
h
SYNC is COMPAX not implemented.
TIME 0010
b
256
100h
1012
h
TIME is COMPAX not implemented.
Point to point objects
EMCY 0001
b
129-255 81
h
-FF
h
1014
h
Error message
Boot-up 0001
b
129-255 81
h
-FF
h
1014
h
Communication readiness
T-PDO1 0011
b
385-511 181
h
-1FF
h
1800
h
Assignment via index 1A00h
Transmit process data object
T-PDO2 0101
b
641-767 281
h
-2FF
h
1801
h
Assignment via index 1A01h
(COMPAX→) max. 8 bytes
R-PDO1 0100
b
513-639 201
h
-27F
h
1400
h
Assignment via index 1600h
Receive process data object
R-PDO2 0110
b
769-895 301
h
-37F
h
1401
h
Assignment via index 1601h (→ COMPAX) max. 8 bytes
T-SDO1 1011
b
1409-1535 581
h
-5FF
h
1200
h
Transmit service data object1
T-SDO2 -* -* -
1201h
Transmit service data object 2
R-SDO1 1100
b
1537-1663 601
h
-67F
h
1200
h
Receive service data object1
R-SDO2 -* -
*
-
1201h
Receive service data object 2
Node guard
1110
b
1793-1919 701
h
-77F
h
100E
h
Checking bus subscriber.
The COB-ID for an object is calculated as follows:
COB-ID = (function code * 128) + device address
The default distribution of the COB-IDs can be changed via SDO after the bus is started.
Application of the communication object types
Transfer of real-time data (faster transmission, as higher priority)
T-PDO Transmit process data object: COMPAX answer (see from page 23).
R-PDO Receive process data object: Transmit to COMPAX (see from page ).18
With the default setting, the transmission of the PDOs takes place at every change of its content.
One-off transfer e.g. of parameters of program lines
T-SDO Transmit service data object: COMPAX answer (see from page ).15
R-SDO Receive service data object: Transmit to COMPAX (see from page ).15
*SDO2 is not configured in the basic state but can be configured via the object with index 1201
h
.