NORD Drivesystems BU0260 - Manual (Page 107)

8 Additional information
BU 0260 GB Subject to technical amendments 107
8.3.2.2 SDO (Service Data Object)
An SDO telegram primarily serves for the exchange of parameter data (for changes in the object dictionary of a
subscriber) and for status queries.
The configuration of functions, i.e. the parameterisation of the frequency inverter is carried out with the aid of
SDOs. However, SDOs are also used for PDO mapping (user-specific specification of the sequence of
process data of a PDO message).
SDO messages have comparatively low priorities. This ensures that messages which are critical for the
process (PDOs, EMCY messages) are handled with priority. SDOs can be transferred in segments if the
necessary amount of reference data is too large for an individual SDO. The receipt of an SDO is confirmed by
the recipient. This ensures the correct exchange of data.
SDOs are processed by CANopen subscribers which are in the status "Pre-Operational" or "Operational".
8.4 System bus
With NORDAC inverter technology, units or modules communicate via a dedicated system bus. With the
introduction of the SK 200E frequency inverter series and the associated components SK CU4-… and
SK TU4-… functions and interfaces were implemented in this system bus, which allow users to make useful
adaptations without having detailed knowledge of the function of the bus system (data allocation / error
handling, etc.).
A decisive advantage is provided by the fact that the system bus is no longer restricted to a single inverter and
a directly connected module, but rather that up to 4 frequency inverters can jointly use a BUS interface (e.g.:
CANopen). This increases the number of possible subscribers on a field bus system (by a factor of 4) with
comparatively low investment costs.
The system bus address of the BUS modules (SK CU4-… and SK TU4-…) is set to "5". The system bus
address of the up to 4 frequency inverters which can be connected are set by means of DIP switches (see
manual BU0200) on the relevant frequency inverter, optionally between 32 / 34 / 36 and 38, whereby no
address may be doubly assigned within a system bus system.