Isel IMD1, Руководство пользователя

Страница: 70 / 117

CanOpen protocol
Positioning module UVE8112, IMD10
SD
node number (node ID) of the device.
O
The Service Data Object (SDO) makes it possible to access the object directory of a CanOpen
device. An SDO always uses two CAN objects with different IDs, since this protocol is always
confirmed. An SDO creates a communications channel between two CanOpen participants. The
device the object directory of which is accessed is the server of this SDO.
Each CanOpen device should dispose of a default SDO. The identifier of the Can objects related to
this default SDO result from a defined Can address plus the
0x600 +
Node ID
SDO Client
SDO Server
Object
Directory
Data
0x580 +
Node ID
Data
Command
Specifier
Index
low byte
Index
High byte
Sub-index
Data byte
0
Data byte
1
Data byte
2
Data byte
3
Data Address Flags
The conten
e.g., if an o t of the first byte of an SDO (Command Specifier) controls the communication and defines
ata bytes can be given in the Command Specifier; it is, however, also defined by the data type of
the object to be transferred.
Basically, there are two different types of an SDO transfer:
•
parameters with a length of 1-4 bytes are transferred with an SDO telegram (Expedited Transfer).
•
data with a length of more than 4 bytes are transferred in several successive SDO telegrams
(Normal Transfer).
In case of the UVE8112 drive module, all parameters can be transferred in the framework of the
“Expedited Transfer”, with the exception of the objects 1008
h
(device name), 1009
h
(hardware
version), 100A
h
(software version) and 2081
h
(trace data). The objects given do not have to be used
in the normal operation.
bject is read or written.
An SDO message always consists of 8 bytes, irrespective of the fact, how many data bytes are really
The unused data bytes can contain any values and have to be ignored. The number of transferred.
d
70