I've got Mach4 running with a PMDX-422 controller. I had it set up, and everything was working fine, including M03/M05. Then my computer gave up, and I had to replace it. I downloaded a new copy of Mach4, got a new license, and downloaded and installed the PMDX plugin. I can run a G-code program and it executes properly, except M03 no longer turns on the spindle.  Mach4 thinks it's on -- the green bar under the "Spindle CW / Stop" display comes on -- but the the power to the outlet controlled by the relay doesn't come on. What am I missing?

you didn't mention nothing about restore mach config from old pc(mach package)
did you forgot this step?

No, I copied over the old profile.

Did you contact the support guys? They may be able to assist you. Seems like a simple setting. Are you in Maine ?

Do you know what output you have the relay setup on?