IMAQdx Snap VI is provided for ease of use as a quick way of making occasional shots. However, citing VI reference:
NI-IMAQdx VI Reference Help:
If you call this VI before calling IMAQdx Open Camera.vi, IMAQdx Snap2.vi uses cam0 by default.
This "feature" is not useful for making quick shots and it makes this VI quite useless in general, because it forces you to manually open and close the camera (what this VI would do as well for unopened camera) every time you want to make a quick shot.
With just a little bit more effort (4 VI vs 3) you can make a usual Grab acquisition.
It's OK to have cam0 as default value, but when Session In terminal is wired please make this VI open the camera which the user actually passed.
It's a very easy change, but making it on a user side is not the best idea.
Consider using the VAS Express VI since this is a single VI that can do Snap or Grab or Ring as well as configure camera attributes, triggers, and works with both IMAQdx, IMAQ, or Simulated camera with folder of images to make it easy to switch from simulated camera to real camera...it does not support wiring in the camera name, so if this is required, you could also make your own helper VI to do what you describe, since I am not sure when the API might be updated based on this suggestion.
Hope this helps and thanks for the feedback.