
30
85201A_RK5C_User Manual_02-2017_ENG
5. PDO SERVICES
The real-time data transfer is performed by means of "Process Data Objects (PDO)". Data type and mapping of appli-
cation objects into a PDO is determined by a corresponding default PDO mapping structure within the object dictionary.
For the PDO1 see object 1A00h.
Communication parameters of the PDO, as COB-ID, transmission mode and transmission frequency, are also specified
in the object dictionary. For the PDO1 see object 1800h.
Since the GEFRAN RK5C CANopen device is a PDO producer, its PDO is also called Transmit PDO (TPDO).
5.1 PDO MESSAGE FORMAT
COB-ID
Rx/Tx
DLC
Data
D0
D1
D2
D3
D4
D5
180h +
Node-ID
Tx
6
Pos
LSB
Pos
Pos
Pos
MSB
Speed
LSB
Speed
MSB
Figure 41 - Transmit PDO1 (TPDO1) message format
5.2 PDO DATA TYPES
Two types of data are mapped in PDO1: Position and Speed.
Position data is an INTEGER32 data type.
Speed data is an INTEGER16 data type.
Assuming that the data is expressed as a bit sequence of length 16 for INTEGER16 data type (b0..b15), and as a bit
sequence of length 32 for INTEGER32 data type (b0..b31), the transfer syntax is explained in the following figure.
Octet number
1
2
3
4
INTEGER16
b7..b0
b15..b8
-
-
INTEGER32
b7..b0
b15..b8
b23..b16
b31..b24
Figure 42 - Transfer syntax for INTEGERn data type
5.3 PDO MAPPING
The PDO mapping type for the GEFRAN RK5C CANopen device is fixed. See object 1A00h description.
5.4 PDO TRANSMISSION TYPES
The PDO transmission type for the RK5 CANopen device can be changed.
There are three types of transmission mode:
1. Synchronous transmission
2. Asynchronous transmission with RTR frames
3. Asynchronous transmission with event-timer
Synchronous Transmission
The transmission of the PDO is performed after the CANopen device receive the n-th SYNC object, when the transmis-
sion type is set to n, with n in the range of 1..240.
The SYNC message format is described in the SYNC services description.