Festo EMCA-EC-67 CO Series, Description

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D CANopen communication
330 Festo – EMCA-EC-C-HP-EN – 2017-11e – English
D.5 SDO message (SDO message)
Through the service data objects SDO (Service data objects), all parameter numbers (PNU) of the FHPP
parameters can be accessed
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SDO communication is carried out through the 2000 series CANopen objects. The SDO
object number consists of the constants 2000h and the parameter number (PNU). The
parameter number (PNU) must be converted into a hexadecimal number.
SDO Index = 2000h + PNU
Example “PNU 100 (= 64h)”:
2000
h
+ 64
h
= 2064
h
SDO accesses are always controlled by the higher-order controller (Host).
Here, one of the following commands can be sent to the EMCA:
– Read commands to read out a parameter
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– Write commands, to change a parameter
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For each command, the higher-order controller receives a feedback message. For the read command, a
response is returned with the read value; for the write command, an acknowledgment is returned.
The design of the commands and responses depends on the data type of the object to be read or writ­
ten. Dependent on the data size, transmission of the data takes place either as expedited transfer (data
size: 1 … 4 bytes) or as a segmented transfer in a 7-byte fragment (data size: 5 … 90 bytes).