jcarmody

Why are you initializing an array in your For loop?  You want to replace elements; here's a very quick way to accomplish that:
 
Also, you don't need to use (ever) the Stop command; just put all of your logic in the other case.

Adding calls to the "Idle" state is an easy way to allow a long process to run without hanging the UI (and without launching an actor).

The easiest way is as ned said, shown in the top image.
 

 
If you can't use a 30-second timeout because you need to handle other things during those 30 seconds, the lower loop will evaluate whether 30 seconds has elapsed every 0.025 seconds.  You'll need to pass the "reset timer' command back into the Timeout event using a Shift Register.
 
Maybe post your VI?
 
Are you really using LabVIEW 2015?

You don't need multiple Case structures for every message if you'll wire ArbIDOrHeader directly to the Case structure you already have.  Just add a new case for every message.  Generally, it's silly to compare a value with a constant to decide which case to execute.  Just wire directly into the structure.