Can you be more specific about what hardware you're using? Here's a list of that NI and Ballard have partnered on:https://www.ni.com/en/support/documentation/supplemental/17/astronics-ballard-and-national-instrumen.... If you can let us know which piece of hardware you're using, it'll help us point you in the right direction. If you're not using any of the hardware on that list, then you may want to reach out to Ballard for help as they'll be more familiar with the hardware that you're using.
The driver for all the products in the previous link can be found here: https://www.ni.com/en/support/downloads/drivers/download.astronics-ballard-avionics-driver.html
If you're using a PXIe-1553 Multi-function model, then the driver should come with an example that has an RT to BC message. Look at BC Compare RT Data with File.vi found in the example folder that comes with the driver.
