I have a dspmc controller on my big Lagun knee mill, and used the MSM screen for a couple of years. Never set-up the probing but have read lots about it on the MSM forum. It has undergone quite a few upgrades, and is now very robust, and also accepts a probe and a touch plate in the same setup. Dave Bagby is very dedicated to answering any questions by MSM users, and making sure the problems are solved. Probing requires a lot of patience to get through the learning curve. MSM has many videos explaining the probing functions.
Your MSM questions should be directed to the Calypso website.
John