Rockwell Automation 20-COMM-K CANopen Adapter User Manual
Page 45
Using I/O Messaging
5-3
20-COMM-K CANopen Adapter User Manual
Publication 20COMM-UM012B-EN-P
Synchronous RPDO: The data of synchronous RPDOs is passed to the
application when the next SYNC object occurs, independently of the
transmission rate specified by the transmission type.
Asynchronous RPDO: The data of asynchronous RPDOs is passed directly
to the application.
PDO Triggering Modes
The adapter supports three PDO triggering modes:
•
Change of State (COS)
Triggering mode COS means that the PDO is sent when a device-specific
event occurs (for example, a value has changed). COS can only be
selected for the TPDO1- Logic Status/Feedback (Parameter 24 -
[PDO1 Trigger] is set to “0”).
COS with transmission mode asynchronous can be configured by setting
the transmission type of the TPDO1 to “254” using a CANopen
configuration tool. For COS with transmission mode synchronous, the
transmission type must be set to “0.”
Adapter Parameters 25 and 26 control the COS behavior. Parameter 25
- [COS Status Mask] defines which bits in the Logic Status word are
checked for changes, and Parameter 26 - [COS Fdbk Change]
specifies how much the Feedback word can change before it is
considered a change of state.
•
Cyclic
PDOs with the cyclic triggering mode are sent periodically with a
specific interval. For the transmission types 0 (synchronous) cyclic
transmission and 254 (asynchronous), Parameter 24 - [PDO1 Trigger]
is set to “1” (Cyclic) and Parameter 27 - [Cycle Interval] defines this
interval. This is only possible for the PDO1.
A synchronous cyclic transmission can also be implemented by setting
the transmission type to a value between 1 and 240. Then, the cyclic
interval is calculated as follows:
Cyclic Interval = Transmission Type x Communication Cycle Period
•
Remote Transmission Request (RTR)
The transmission of a PDO is initiated on receipt of a Remote
Transmission Request initiated by any other device (PDO consumer).
The transmission can be either synchronous or asynchronous.