Drive function
enabled
No No No No Yes Yes Yes No
Configuration
allowed
Yes Yes Yes Yes No No No Yes
The devices of the motion control system are configured by the Service Data Objects (SDO) while the real-time
process data is transferred by Process Data Objects (PDO).
3.1.2.2 PDO
PDO (Process data objects) are used in EtherCAT to cyclically transfer in real-time control (e.g. target velocity)
and status (e.g. current velocity) variables. These variables are identified by their Index and Subindex in the
object dictionary. With the help of the PDO mapping, the objects from the object dictionary are assigned to
either receive PDO (RxPDO, Master to Slave direction) or transmit PDO (TxPDO, Slave to Master direction).
PDO data is internally updated by the slave (servo drive) at a rate of up to 4kHz and can be accessed by the
master (e.g. PLC, Motion Controller) at any desired frequency.
For more information about PDO refer to ETG1000.5 and ETG1000.6
3.1.2.3 PDO Configuration
SOMANET supports EtherCAT PDO Configuration for up to 20 objects on 4 maps. This allows to use up to 80
objects per direction.
PDO Config allows to change the mapping of the PDO mappings itself. Every PDO mappable object from the
object dictionary can be added into a PDO mapping. It is possible to add up to 20 objects to one PDO mapping
3.1.2.4 SDO
SDO (Service Data Objects) are used to exchange parameters between master and slave devices in a EtherCAT
Network. This isn’t done in real-time. They provide read and write access to all entries in the device object
dictionary.
Typical examples are:
Configuring the Drive system
Reading error codes
For more information about SDO refer to ETG1000.5 and ETG1000.6.
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