Siemens MICROMASTER 420 Operating Instructions Manual page 47

Issue 01/05
PDO data transfer types
CANopen makes a differentiation between various data transfer types (trigger
events for the PDOs).
The various data transfer types for PDOs is shown in the following table:
Table 3-11
Data transfer type
0
1 - 240
241 - 251
252
253
254
255
Significance of the various data transfer types:
Non-cyclic synchronous transfer
Cyclic synchronous data transfer
RTR, synchronous data transfer
RTR, non-synchronous data transfer ⇒ The value is immediately sent after an
Non-synchronous
Synchronous PDOs are transferred using the standardized SYNC object. The
SYNC Producer sends these periodically.
CANopen Option Module Operating Instructions
6SE6400-5BC00-0BP0
PDO data transfer types
PDO data transfer
Cyclic Non-cyclic
X
Data transfer using CANopen
Synchronous
synchronous
X X
X
Reserved
X
⇒ If a value has changed, it is sent after
each SYNC telegram
⇒ A value is sent (n = 1 - 240) after each
th
n SYNC telegram
⇒ After an RTR query has been received,
after the next received SYNC message,
the value is sent.
RTR query has been received.
⇒ Non-synchronous PDOs are always sent
if an event has occurred (the value has
changed). Data transfer types 254 and
255 differ as follows: For 254, the trigger
has a manufacturer-specific origin. For
255, the trigger is received from an event
defined in the profile. In order to receive
the PDO in a specific cycle, in spite of
the non-synchronous data transfer, even
if the value did not change, in the
communication objects event timers can
be set which means that PDOs are sent
after the selected time.
Non- RTR
X
X X
X
X
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