Burkert Type 8717 - Manual (Page 43)

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CANopen Start-up
6.3. Canopen – Service Data Transfer
data transfer between two nodes is described in the client/server model. An SdO client (initiating node) has
direct access to individual entries in the object directory of an SdO server and is able to upload or download data
records of any length to or from a server. The data record to be transferred can be specified by indicating a 16-bit
index and 8-bit subindex. Since one message identifier is required for each transfer direction, two CAN identifiers
are required for a connection between an SdO client and an SdO server. The connection between a client and a
server is also referred to as an SdO channel.
The Bürkert field device has an SdO channel and supports the following transfer types:
Segmented transfer
Segmented transfer makes it possible to transfer 7 bytes per transfer sequence. At the beginning, an initialization
sequence a 16-bit index and 8-bit subindex is transferred. This is followed by confirmed, segmented transfer of
data.
expedited 1) transfer
Expedited transfer allows for faster transfer of 4 bytes per transfer sequence. It is normally used whenever the
size of the data being transferred does not exceed 4 bytes.
An SdO message is structured as follows:
Id dLC Byte1 Byte2 Byte3 Byte4 Byte5 Byte6 Byte7 Byte8
- 8 CMd Index Subindex data bytes
The transfer is specified in byte 1 by control bytes. For an overview of the meaning of different control bytes, see
the following table.
process cmD note
Master requests data from slave 40h
Slave responds 42h (valid data bytes not specified)
43h (4 valid data bytes)
47h (3 valid data bytes)
4Bh (2 valid data bytes)
4Fh (1 valid data byte)
Master writes to slave 22h (valid data bytes not specified)
23h (4 valid data bytes)
27h (3 valid data bytes)
2Bh (2 valid data bytes)
2Fh (1 valid data byte)
Slave responds 60h
1) Expedited: accelerated
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