30
The objects or parameters are addressed with a 16-bit index and an 8-bit subindex. The
build-up of the object dictionary and the access to it is described in the following
chapters. CANopen defines different objects for communication.
These are:
-
Service Data Object (SDO):
For parameter settings
-
Process Data Object (PDO):
For transmitting process data
-
Network Management Object (NMT):
For changing the state of a device
-
Emergency Object:
For transmitting error and alarm messages
-
Timestamp Object:
For adjusting the time
The differentiation of these communication objects results from the identifier. The
identifier is separated in two parts.
The most significant 4 bit describe the function code which declares the type of the
message, the remaining 7 bit describe the Node ID.
This separated identifier is called the Communication Object Identifier (COB-ID).
Therefore it is possible in this broadcast system to communicate with single
participants.
Functions code
Node ID
Bit10 Bit9 Bit8 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
The meaning of the function code is arranged in the so-called Pre-defined connection
set.
Object
Function code (binary)
Resulting COB-ID (dec)
NMT
0000
0
SYNC
0001
128
EMCY
0001
129 - 255
PDO1 (tx)
0011
385
– 511
PDO1 (rx)
0100
513
– 639
PDO2 (tx)
0101
641
– 767
PDO2 (rx)
0110
769
– 895
PDO3 (tx)
0111
897
– 1023
PDO3 (rx)
1000
1025 - 1151
PDO4 (tx)
1001
1153
– 1279
PDO4 (rx)
1010
1281
– 1407
SDO (tx)
1011
1409
– 1535
SDO (tx)
1100
1537
– 1663
NMT Error Control
1110
1793 - 1919
5.2. CANopen
– functionality
The CCM01 does not have the complete CANopen
– funtionality.
The following functions of CANopen are available:
-
Object dirctionary with all measured data and parameters
-
One SDO-Server
For parameter settings
-
One transmit PDO
For transmitting the measured data
-
Nodeguarding or Heartbeat
-
Emergency object for error or alarm messages
-
Timestamp for adjustment of time
-
NMT-State-Machine
5.3. Start-up
For starting the controlling with CAN you must proceed as follows.