RS485 Spindle Control

Hey,

I have a Mesa 7i95t board that to my understanding has support for RS485.

I want to connect my Delta MS300 VFD to LinuxCNC over RS485, and I think I have two options:
* I've got a USB RS485 dongle that I can connect to the PC and to the VFD on the other end
* I can connect the Mesa board's RS485 terminals to the VFD

Which one of these options are preferable? Are both these options correct, and are there any pros/cons to either?

Thanks!