STOBER 10 | Looking for more information about EtherCAT?
02/2020 | ID 442516.07
59
10.3.2.2 Expedited transfer
The simplified, expedited SDO transfer is used for transferring all parameters with a data type of maximum of 4 bytes. In
this type of transmission, 4 data bytes are sent in a single frame. The data is arranged in accordance with the Intel format
(little-endian), meaning that the byte with the smallest value is saved at the starting address and transmitted first (compare
with big-endian or Motorola format, where the highest-value component is sent first).
Write parameter (Initiate Domain Download Request)
The master uses an Initiate Domain Download Request to initiate a write process for a communication parameter. The
request receives a positive acknowledgement from an Initiate Domain Download Response of the slave.
Byte 1 2 3 654 7 8
0x23 LSB MSB MSBLSB LSB MSB
Master Slave
Command Index
Sub-
index
LSW data MSW data
Byte 1 2 3 654 7 8
0x63 LSB MSB MSBLSB LSB MSB
Command Index
Sub-
index
Unused
Read parameter (Initiate Domain Upload Request)
The master uses an Initiate Domain Upload Request to initiate a read process for a communication parameter. The request
receives a positive acknowledgement from an Initiate Domain Upload Response of the slave.
Byte 1 2 3 654 7 8
0x40 LSB MSB MSBLSB LSB MSB
Master Slave
Command Index
Sub-
index
Reserved
Byte 1 2 3 654 7 8
0x42 LSB MSB MSBLSB LSB MSB
Command Index
Sub-
index
LSW data MSW data
Error message (Abort Domain Transfer)
A slave provides a negative response to the write parameter or read parameter requests using an Abort Domain Transfer
(see SDO transmission: Error codes [}81]).
Byte 1 2 3 654 7 8
0x80 LSB MSB MSBLSB LSB MSB
Master Slave
Command Index
Sub-
index
Additional
code
Error
code
Error
class