I am a beginner. I have 2 Arduino uno cards. My XP machine has 4 usb on the back and 2 in the front. The Arduino program sees 1 card on USB4 and the other card on USB5. Vixen only sees the one on USB4. Where are the other USB ports in Vixen? Don't I need a USB port for each group of 8 channels? I was thinking I needed chan1-8 on usb4 and chan9-16 on usb5. Am I missing something?