ICP DAS USA CAN-8823 User Manual page 32

For the CANopen device, the TxPDO specializes in transmitting data, and
is usually applied on DI/AI channels. The COB-ID of the PDO for receiving
data is RxPDO COB-ID, and it is usually applied on DO/AO channels. Take the
CAN-8x23 as an example. If a PDO producer sends a PDO message to the
CAN-8x23, it needs to use the RxPDO COB-ID of the CAN-8x23 because it is
a PDO reception action viewed from the CAN-8x23. Inversely, when some
PDO consumers send remote transmit requests to the CAN-8x23, it must use
the TxPDO COB-ID of the CAN-8x23 because it is a PDO transmission action
viewed from the CAN-8x23.
Trigger Modes Of PDO
For PDO producers, PDO transmission messages can be trigged by three
conditions. They are the event driven, timer driven and remote request
conditions. All of them are described below.
Event Driven
PDO transmission can be triggered by a specific driven event, including
the following conditions. Under the cyclic synchronous transmission type, the
event is driven by the expiration of the specified transmission period,
synchronized by the reception of the SYNC message.
Moreover, under the acyclic synchronous or asynchronous transmission
type, the PDO transmission can also be triggered or driven by a
device-specified event in the CANopen specification DS-401 v2.1, i.e. by
following this spec, the PDO will be triggered by any change in the DI-channel
states when the transmission type of this PDO is set to acyclic synchronous or
asynchronous.
Timer Driven
PDO transmissions are also triggered by a specific time event, even if a
specified time elapsed without occurrence of an event. For example, the PDO
transmission of the CAN-8x23 can be triggered by the event timer of the PDO
communication parameters, which is set by users.
Remote Request
CAN-8x23 user's manual (Revision 3.20, Mar/08/2012) ------ 32