Object types
COMPAX CANopen
Unsigned
8
5 Object types
Each object type is determined by a
C
o m m u n i c a t i o n
O
b j e c t
I
d e n t i f i e r (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).
C
o m m u n i c a t i o n
O
b j e c t
I
d e n t i f i e r :
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
.
