I have a question that xem6310 support usb3 cable, and the the wirein and triggerin are now 32-bit wide. What if in fpga design i use usb 3 modules, but connect the board to pc with a usb2 cable. Does it cause any problem?
No, this will not create a problem. The design is the same in both situations. The ONLY difference is that the performance will downgrade to USB 2.0 performance.