BUDE_Manual-CANopen_EN.doc
12/55
Baumer Hübner GmbH
23.10.2012/bja
Berlin, Germany
SDO examples
Request
of a value by the master from the slave
A frequent request will be a request for position.
Object 6004h
COB ID
DLC Command
Object L
Object H Subindex Data 0
Data 1 Data 2 Data
3
600h+node ID
8
40h
04h
60h
0h
x
x
x
x
Response
by the slave
to the request
for a value
The position is 4 bytes long, the precise values can be found under object 6004h.
COB ID
DLC Command
Object L
Object H Subindex Data 0
Data 1 Data 2 Data
3
580h+node ID
8
43h
04h
60h
0h
a
b
c
d
Writing
of a value by the master into the slave
Position setting can be performed with preset.
Object 6003h
COB ID
DLC Command
Object L
Object H Subindex Data 0
Data 1 Data 2 Data
3
600h+node ID
8
22h
03h
60h
0h
a
b
c
d
Slave's
response
to the
writing of a value
COB ID
DLC Command
Object L
Object H
Subindex Data 0 Data 1 Data 2 Data
3
580h+node ID
8
60h
03h
60h
0h
0h
0h
0h
0h
3.3.4
Process data communication
Process data objects are used for real time data exchange for process data, for example position or
operating status. PDOs can be transmitted synchronously or cyclically (asynchronously). The
encoder/converter supports the PDO1 and the PDO2. Both PDOs supply the current position of the
encoder/converter and are defined in the objects 1800h, 1801h, 1A00h, 1A01, 2800h, 2801h and 6200h.
Synchronous
In order to transmit the process data synchronously, a value between 1 and F0h (=240) must be written into
the object 1800h / 1801h Subindex 2. If the value is 3, the PDO is transmitted on every third sync telegram (if
the value 1 is entered, transmission takes place on every sync telegram), as long as there is a 0 written into
the object 2800h / 2801h. If it contains for example a 5, the PDO will continue to be written as before on
every third Sync telegram, but only a total of 5 times. Accordingly, the last PDO is written on the 15th sync
telegram. The counter for the number of PDOs to be transmitted is reset in the event of a position change or
NMT reset, i.e. unless it is changed, the position is transmitted five times. If the position changes, it is
transmitted a further five times.
In synchronous operation, the PDO is requested by the master via the Sync telegram.
Byte 0
Byte 1
COB ID = 80
0h
