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7
Data transmission with PDO and SDO
ID 441896.05
WE KEEP THINGS MOVING
Operation manual
30
7.2
Parameter Transmission with SDO Service
All the parameters of the CANopen
®
DS-301 inverter can be read and written with
the SDO service. The SDO service always transmits data in 4-byte integer format
(except for strings).
The controller starts a job with an SDO request. The controller uses this request
to select a communication object (parameter) with index and subindex. The object
directory with the list of all available parameters is searched on the inverter, based
on these variables, and the service is executed. The inverter then responds with
the appropriate SDO response.
The SDO messages are transmitted with the mailbox service of EtherCAT. shows
the structure of an SDO message.
Fig. 7-2 Structure of an SDO message
The mailbox consists of the mailbox header and the mailbox data. The header
indicates that the data contain a "CANopen
®
over EtherCAT" telegram. The
telegram consists of the COE header and the COE data. The COE header
specifies that the following data contains an SDO request message.
shows the structure of the mailbox header.
Fig. 7-3 Structure of the mailbox header
The
Length
field contains the number of bytes in the mailbox following the header.
The Address field contains the EtherCAT address of the respective slave. The
Type
field states which protocol is located in the mailbox. Enter the value "3" for
CANopen
®
over EtherCAT here. The other fields (
Channel
,
Priority
and
Reserve
)
are not needed. Each of them remains 0.
Mailbox-Header
6 Byte
2 Byte
8 Byte
CoE-
Header
Expedited SDO-Message
Le
ngth
16 bits
16 bits
6 bits 2 4
4
A
ddr
ess
Chan
nel
Priority
Ty
p
e
In res
.