Instruments with same Ip address

Hi all,

I'm using Pl303-P Power supply for experiment. 

I control it by TCP/IP protocol with VISA VI (classic open,write,read,close).

For practical reasons, i'm using LAN/USB adaptators to communicate by LabVIEW.

In my experiment, i have to control 2 resitances with 2 units dedicated.

The metter is appear when i connect both units on USB ports. Only one is recognized and i think they have the same address IP. 

I wanted to know how can i assign two different address?  

i use this reference of adaptator: http://www.dexlan.com/dexlan-adaptateur-usb-20-rj45-ethernet-10100-xml-2447_2474_2475_2487-29622.html

Thanks in advance, 

V.T