Hi,
Mach3 and Mach4 are designed differently.
Mach3 was designed specifically with the Parallel port in mind whereas Mach4 is more designed around hardware flexibility.
For Mach4, always make sure that you have the correct plugins enabled. In your case the UC100. Make sure that this device is selected as your motion controller. This will allow Mach to send motion commands to your UC100. From there, You set up your motor information in your UC100 plugin. Most motion controllers you can skip this step as it is not needed. After you go through your UC100 configurations, You can go into your Mach configs and setup things like steps per unit, acceleration, Velocity, Inputs, and Outputs.
When you do things like try to get motion, first verify that your drives are enabled. If your drives are not enabled you will not get motion. Next verify that you have the correct step and direction polarity, and finally, verify your wiring. These are the most common issues when it comes to getting setup.
Terms:
Inputs: This is an input signal. Mach is looking for an signal to tell it to do X thing.
Output: This is an output signal. Mach is telling something to do X thing when triggered.
Your limit, home, and ESTOP switches will be an input.
Your Pumps, Lights, Solenoids, Enable signals will be outputs.
If it is all set up and you're still having issues, there is a chance your firewall could be blocking the signal to your UC100. Try opening the firewall port and see if that makes a difference.