Siemens SINAMICS S120 Installation And Start-Up Manual page 18

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1.3 Terminology
Node ID (node identification)
Uniquely identifies a device in the CANopen network. For this reason, all the devices must
have a unique node ID (bus address). The default distribution (standard setting) of the COB
IDs is derived from the node ID. In this documentation, node IDs are always specified as
hexadecimal values.
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 PDOs and SDOs
• The data that is assigned to the PDOs
• The time at which the PDOs are 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. Mappings of certain PDOs are
preconfigured for certain variables or groups of variables.
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. PDOs provide fast, real-time access
to selected variables.
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Commissioning Manual, 12.2004 Edition, 6SL3097-2AA00-0BP1
CANopen interface