Hello,
Based on your username, it appears you are using USB-CAN. Because this is a low-cost device, it doesn't have the on-board processor of the higher-end cards to do on-board periodic transmits. Tthis is documented in the online help and in the manual. This DevZone also has some more details of what is support amongst the various CAN product lines:
http://zone.ni.com/devzone/cda/tut/p/id/5859In this scenario, I recommend setting up a Timed Loop with the CAN Write Frame function in it for the frequency of the broadcast message you need. This will function well for a majority of applications.
The Example Finder can also filter examples for those that have been tested with the USB-CAN interfaces by using the hardware drop-down in the lower-left corner and selecting the "Limit Results to Hardware" option.
Hope this helps!
--Paul Mandeltort
Automotive and Industrial Communications Product Marketing