CANopen Programmer's Manual - Maccon.de

CANopen Programmer’s Manual 1: Introduction
Segmented, Expedited and Block Transfers
As in the example above, most SDO transfers consist of an initiate transfer request from the
client, followed by series of confirmed eight-byte messages. Each message contains one byte of
header information and a segment (up to seven bytes long) of the data being transferred.
For the transfer of short blocks of data (four bytes or less), the Communication Profile specifies an
expedited SDO method. The entire data block is included in the initiate SDO message (for
downloads) or in the response (for uploads). Thus, the entire transfer is completed in two
messages.
The Communication Profile also describes a method called block SDO transfers, where many
segments can be transferred with a single acknowledgement at the end of the transfer. Copley
Controls CANopen amplifiers do not require use of the block transfer protocol.
Copley Controls 23