Modbus RTU serial Rs485 and Modbus TCP Ethernet protocol

I have a Third party H/w have Modbus RTU and TCP interface option.How  can i  communicate to this device through Labview.

i) How to select the NI module for physical interface and API for the same?

ii) Is any serial to usb converter(third party converter) can do the same thing?

iii) For both RTU and Tcp can we use a same Physical interface(serial converter or NI Module)??