The extract from this document should answer your question :
There are two APIs (application programming interfaces) exposed with the NI-CAN driver software. The Frame API is the original API for CAN programming. In the Frame API, you can transmit and receive CAN frames that contain raw data bytes. Your program must parse and scale these bytes to come up with scaled engineering units. For more information on programming with the Frame API, please consult the Using the Frame API section of the NI CAN Hardware and Software Manual (see below).
NI first introduced the Channel API in the NI-CAN 2.0 driver software. You can read from and write to CAN channels using channel names defined in database files (.dbc or .ncd). The Channel API provides the following benefits:
- High-level programming
- Easy-to-use physical units
- Primary use for easy CAN/data acquisition synchronization
- Ability to incorporate Vector database files
For more information on programming with the Channel API, please consult the NI-CAN Channel API resource below.
See Also:
Download the latest National Instruments CAN software
The NI-CAN Channel API
NI CAN Hardware and Software Manual
