Hi,
I've just re-read the manual, what there is of it, and I think my previous post is wrong. It says the 12-24V supply is optional.
Can you post your xml file, may be we can spot a problem in the setup.

Craig

As I understand the 12-24V power is required only if you are going to have limit switches and an E stop button.  I have a 15V power supply attached to the board but have not been able to get a signal to Mach3 when I close the one limit switch attached to the board when looking at the inputs screen. 
Not sure what you mean for me to post my xml file.  Is it the Mach 3 setup file?
Thanks
Dale

If I'm using usb with a UC100 motion controller, do I have to pick a port like when using a parallel port?

Hi Dale,
even if you don't want limit switches you will still need an Estop therefore the 12-24V supply is required.

Pick port 1 although the UC100 makes the selection a moot point.

Yes, an .xml file is all the Mach setup data. On the lower right of the Mach screen is the current profile name.
Find it in your Mach3 folder and make a copy name dale.xml. Post the copy.

Craig

You need to assign port 1 when setting up the pin numbers, for all of your inputs and outputs.

Putting in port 1 solved the problem.  Motor running fine.  I'm going to hook up the other motors and switches.  Thanks for all the help.  This forum is great.  Dale

Are we ever going to have a version of Mach that joins the rest of us in the 21 century?

If you want to use a printer port with Windows 10, then no.
Otherwise, Mach3 and Mach4 run fine in Windows 10.

Keep in mind that development of Mach3 stopped about 5 years ago, so you'll never see another version of it.

Will using a USB motion controller for Mach3  work in Windows 10 32 bit or 64 bit?

If you use a USB or ethernet motion controller from a reputable company, you shouldn't have any issues. My preference is CNC Drive controllers, as they have excellent support, and are constantly updating their firmware.