Festo EMCA-EC-67 CO Series, Описание

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D CANopen communication
322 Festo – EMCA-EC-C-HP-EN – 2017-11e – English
D.3 CAN-bus access
D.3.1 Access via data objects (PDO/SDO)
CANopen makes available a simple and standardised possibility to access the parameters of the EMCA
(e.g. the positioning speed). A unique number (index and subindex) is assigned to each FHPP paramet­
er (PNU). All of the FHPP parameters are included in the “FHPP parameters” overview
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page 241.
Two methods are available for accessing CANopen objects via the CAN bus:
– Access via Service data object (SDO):
Confirmed access type, in which the EMCA acknowledges each parameter access
– Access via Process data object (PDO):
Unconfirmed access type, in which no acknowledgement is made
As a rule, the EMCA is parametrised via SDOs and controlled via PDOs.
Confirmation of the
EMCA
Order from the con­
troller
controller EMCA
Data (actual val­
ues) for the con­
troller
controller EMCA
Data (setpoint val­
ues) from the con­
troller
controller EMCA SDO (Receive)
SDO (Transmit)
SDO communication PDO communication
RPDO (Receive)
Control data
TPDO (Transmit)
Status data
Fig. D.3 Access procedure over data objects
Byte format
With CANopen, the 16-bit values (word) and the 32-bit values (double word) are presen­
ted in the “Little endian” byte format (least significant bit (LSB) first)
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page 125.