User Manual

POSI+ CANOPEN USER MANUAL
Version 1.02 Page 11
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2.3. Process data communication
Process data objects are used for real ti me data exchange for process data :po sition. PDOs can
be transmitted synchro nously or cyclically (asynchronously). The encoder supports the PDO1
and the PDO2. Both PDOs supply the current position of the encoder and are defined in the
objects 1800h,1801h, 1A00h, 1A01.
Synchronous
In order to transmit the process data synchronously, a value between 1 and F0h (=240) must be
written into the object 1800h / 1801h Subi ndex 2. If the v alue is 3, the PDO is transmitted o n every
third sync telegram (if the value 1 i s entered, transmission takes place on every sync tel egram)
In synchronous operation, the PDO is requested by the master via the Sync telegram (COB-ID =
80h).
Cyclical (asynchronous)
If you wish the PDOs to be transmitted cyclically, the value FEh must be written into the object
1800h / 1801h Subindex 2. In addition, the cycle ti me in milliseconds must be entered in the same
object subindex 5 . The ente red time is rounded off to 1 ms. If the v alue i s stored for 0 ms, th e PDOs
are not trans mitted. Th e function is swi tched off.
Response to an RTR message
by means of the remote frame = recessive RTR bit, precisely the message with the transferred
identifi er will be requested
Transmission of the current position
The process value is sent on the CAN network with the following message:
COB-ID Process value
11 bits Byte 0 Byte 1 Byte 2 Byte 3
2
7
to 2
0
2
15
to 2
8
2
23
to 2
16
2
31
to 2
24
The COB-ID contains the node number and the corresponding PDO(tx). By default, the sended
process value use the COB-ID 0180h+Node-ID and, in response to the SYNC message, use the
COB-ID 0280h+Node ID .
The PDO COB-ID are defined in the object 1800h/1801 h subindex 1.