CANopen Data Communication Protocol
15
Data is transmitted through a variety of Communication Objects (COB) in the
CANopen data frame.
Process Data Objects (PDO) are used to transmit the data requiring real-time
transmission (Real-time data), while Service Data Objects (SDO) are used to transmit
the data that does not require real-time transmission.
4.1.2 SDO Communication
SDO communication is used for Peer-to-peer data communication between two
CANopen devices, which does not require real-time transmission (Ex: setting the
parameter values).
SDO communication accesses objects with the combination of the object index and
sub-index, and allows for reading and writing of all the objects in the object directory.
4.1.3 PDO Communication
PDO communication is used to send and receive data requiring real-time transmission
(real-time data). Data is transmitted without overhead or confirmation of the protocol
(index, sub-index, and data). Such features make PDO communication useful for IO
communication.
PDO communication can be divided into two types depending on the transmission
direction; RPDO (Receive PDO) for receipt of data from the master device and TPDO
(Transmit PDO) for transmission of data to communicate with the master device.
The G100 CANopen communication module is available for PDO communication for
frequency conversion that is supported by the CiA 402 Drive and Motion Control
device profile (only PDO1 and PDO3 communications are supported).
PDO1 and PDO3 communications cannot be utilized at the same time.
