Transmission Of Sdo Messages - TR-Electronic 65 Serie Gesamt-Bedienungsanleitung

POWERLINK Information

3.7 Transmission of SDO messages

The entries of the object dictionary can be read or written with the SDO services. The
SDO Transport Protocol allows the transmission of objects of any size.
Services with confirmation (Initiate SDO Upload, Initiate SDO Download, Download
SDO Segment, and Upload SDO Segment) and services without confirmation (Abort
SDO Transfer) are used for the execution of Segmented/Expedited transmission of
Service Data Objects.
The so-called SDO Client (MN) specifies in its "Request" the parameter, the access
type (read/write) and the value if applicable. The so-called SDO Server (CN or
measuring system) executes the write or read access and answers the request with a
"Response". In the case of error, an error code (Abort SDO Transfer) provides
information on the cause of the error.
The measuring system supports SDO transmissions over UDP/IP and EPL Asnd
frames in the asynchronous time period.
MAC-Frame-Header
(EtherType = 0800h)
Figure 8: EPL compliant UDP/IP frame structure
Normally the POWERLINK master provides appropriate mechanisms for the SDO
transfer. Knowledge of the protocol structure and internal sequences is therefore not
required.
Write services, Client --> Server
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Read services, Server --> Client
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IP-Header
(Protocol = 0x11)
Initiate SDO Download Expedited
The Expedited SDO Download service is used for the accelerated
transmission of data which can be transmitted with one Ethernet frame.
The server responds with the result of the download request.
Download SDO Segment
The SDO Download Segment service is used to transfer the additional data
that could not be transferred with the Initiate SDO Download service. The
master starts as many Download SDO Segment services as are required
to transfer all data to the server.
Initiate SDO Upload Expedited
The Expedited SDO Upload service is used for the accelerated
transmission of data which can be transmitted with one Ethernet frame.
The server responds with the result of the upload request and the required
data, in the event of successful execution.
Upload SDO Segment
The SDO Upload Segment service is used to transfer the additional data
that could not be transferred with the Initiate SDO Upload service
response. The server starts as many Upload SDO Segment services as
are required to transfer all data from the server.
TR - ECE - BA - DGB - 0071 - 05
UDP-Header
(Port = 0xXXXX)
EPL Content CRC
Printed in the Federal Republic of Germany
06/26/2017