84 • CANopen
Network
Communication
WAGO-I/O-SYSTEM
750
CANopen
4.3.1.1.1 PDO Protocol
This protocol is used to transmit data from/to the bus coupler without protocol
overhead. PDOs consist only of the CAN identifier and the data field. No fur-
ther protocol information is contained in a PDO. The contents of the data are
defined by the mapping parameters and the transmission type by the commu-
nication parameters.
A differentiation is made between RxPDO (receipt PDO) and TxPDO (trans-
mit PDO).
Client
Receive Process Data Object (RxPDO)
COB-ID = yy
Data
0
8
Server
Fig. 4-1: RxPDO
g012403x
Client
RTR-Frame, COB ID = xx
Transmit Process Data Object (TxPDO)
COB-ID = xx
Data
0
8
Server
Abb. 4-2: TxPDO
g012404x
4.3.1.2 Service Data Object - SDO
The SDOs can be used to read and/or write entries in the object directory. In
this manner, a CANopen subscriber can be fully configured. The default SDO
is pre-assigned with a low priority identifier. The transmitted data has to be
distributed to several messages if it exceeds 4 bytes.
