Rockwell Automation 20-COMM-K CANopen Adapter User Manual

Page 45

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Using I/O Messaging

5-3

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:

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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.

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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.

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