Siemens Sinamics S120 Commissioning Manual page 147

OD (object directory)
A "database" – or object directory – containing all the objects supported by a drive is defined
for each drive unit. The object directory contains:
● Type, description, and serial number of the device
● Name, format, description + index for each object
● Lists of PDO, SDO
● Which data is assigned to the PDO?
● When are PDO transmitted? (SYNC, change in object, etc.)
● The time at which emergency messages are transmitted
● ...
All the drive unit variables are accessed via objects. The SDO and PDO communication
services access the object directory of the drive unit.
PDO (process data object)
Used for accessing selected data rapidly and in real time. For certain variables, mappings to
certain PDOs are preconfigured.
The SDO is used to access all the other variables.
Profile
In the case of communication with bus systems, profiles are documents used for device
standardization purposes, whereby communication functions (in a communication profile),
device functions (in a device profile), or drive functions (in a drive profile) are described from
the point of view of the communication interface.
RPDO (receive PDO)
PDO is received by the device (contains the final position, for example).
SDO (service data object)
The SDO provides access to all variables in a CANopen device (in the case of drives: drive
and CANopen variables).
The SDO is generally used for configuration purposes. PDO provide fast, real-time access to
selected variables.
CANopen interface
Commissioning Manual, 11/2017, 6SL3097-4AA00-0BP3
Appendix
A.3 CANopen glossary
147