This doesn't really fit with your statement that it works in 8.5 and not in 8.6, but just for a sanity check, I would try to open the port with Hyperterminal. If you can't open it there, it could be that the other program that is using the port is not releasing it properly.
QUOTE(alfa @ Feb 11 2008, 01:22 AM)
Has alfa been using LabVIEW to find this connection?
http://zone.ni.com/devzone/cda/tut/p/id/6957?metc=mt9x7' target="_blank">Overview of Human Vibration Weighting Filters
Could you have LabVIEW poll the meter until it sees a steady value in the correct range? If you wanted to get a little fancy, you could include a sketch of the board that shows where to put the probes for each measurement.
Another route would be to make your own trigger, maybe something foot operated so the tech can use both hands for the probes. This would be easy to do if you have a daq card; I'm pretty sure you could rig something up using the parallel port too.
In the LabVIEW help go to Fundamentals -> Development Guidelines -> LabVIEW Style Checklist and Fundamentals -> Managing Performance and Memory -> Concepts to get some basic do's and dont's. Here you will find the following advice.
QUOTE(LabVIEW Help - VI Execution Speed)
One of the big selling points for LabVIEW is that it is easy (compared to other programming languages) for people with little experience to get a program to "work". Unfortunately that can lead to some pretty ugly code.