The Ph Pro already has a built in interface, all you need is a serial to USB cable such as this one sold by RR-Cirkits: UN8-BE
If you have a cable but cant find drivers. Try these:
This cable is a USB to Serial Interface DB9 Connection using the RS232 protocol for sending binary commands. Includes driver disk. Well suited for interfacing NCE command station to USB.This unit does not require any modifications to the command station for proper attachment. Also useful for other serial devices.
Maximum cable length is 50 feet, or the cable length equal to a capacitance of 2500 pF. The latter rule is often forgotten. This means that using a cable with low capacitance allows you to span longer distances without going beyond the limitations of the standard.
Be aware that MANY low cost FTDI or USB to serial cables use counterfeit clone FTDI chips which DO NOT WORK. Google this issue for more details.
Do not attempt to install or run JMRI or any other software until AFTER the driver is installed and configured correctly. If this has been done prior to driver installation remove JMRI and all folders that were created during the installation. Now reboot the PC. Follow the directions that come with the cable for driver installation. Next check to see if the driver installed correctly. Go to:
Start\Settings\Control Panel\Device Manager.
Look for the Ports section, click on the arrow, The exact listing under ports will vary but it should look something like this:
If you are using JMRI, the JMRI status bar will look like this:
If nothing is listed under ports, look for a listing under the heading of "other". If it is listed under "other" or "unknown" the driver needs to be manually installed. Use the disk that came with the cable to install the driver manually.
This would be a good time to run a drive cleaner to clean up the pc before installation of JMRI. I use CCleaner by Piriform. https://www.piriform.com/ccleaner/download Use this at your own risk but I find it an invaluable tool for cleaning PC's.