I have my smoothstepper powered from my PMDX126 board via the ribbon cables.
The problem I'm seeing, if I ever start up mach3 with my control box not powered, or if I cycle the powere to the control box, I get endless dialog boxes stating there were Read and Write Errors.
The problem is, you can power the control box back up and these endless dialogs never go away and you can not escape from them without doing a 3 finger salute and End Task.

Is there a way to fix the above endless loop?

I figure I could power the smoothstepper from USB and leave the PMDX126 powered by it's AC Mains, but won't that start causing issues with different power supplies and grounds?

Thanks,
Richard

Powering the SS from either USB or a separate 5v power supply won't cause any problems. That's the way I've done it on a couple installs, and it works fine. USB is the simplest, but a stand alone little 5v power supply works, too. I've actually never powered the SS thru the 26 pin cable from my PMDX boards!! I forgot you could do that! I have my SS mounted inside the computer case with headers to the back plane and I use normal DB25 cables to the machine control box and thus the PMDX-126. I can, if I want to test for some reason, switch to parallel port and it's just a matter of swapping cables on the computer end and making sure Mach3 is setup right.

The problem is that the SS plug-in perceives loosing communication with the SS as a show stepping error, which in truth it is because there is no good way for the SmoothStepper plug-in to reset itself to Machs current state (a limitation of how mach deal with external motion control devices.) So you have to restart Mach so it and the external motion device can get back in sync.

It would be nice if the error messages were limited though.