Hello Matthew,
What NI CAN card are you using? Also, what other CAN device are you communicating with using this CAN card?
Can you describe in more detail what you mean when you say there is a lag in the data? How long is the lag in the data, and is it just an offset or does it read too slowly for the rate data is coming in (and therefore fall behind)?
Finally, have you tried using some of the examples in the example finder? (Help --> Find Examples --> Hardware Input and Output --> CAN --> NI-CAN)
Colden Rouleau
Product Support Engineer | NI-RIO R&D | National Instruments