Yes PMDX is still in business.
I have talked to Steve personally and he has moved his business to his home and is in the process of putting everything together, so if you need to have an issue resolved ,firsty send him the information that he requires and then call him right now that is the best solution.
I was having a major issue with my 416 board and he was able to find out that their is a plugin issues that has to be resolved so the 416 board works properly with Mach 4.
This will take awhile so if you are having communication errors with Mach 4 and 416 motion controller , he is working on this issue
Thanks