Hello Rst,
Did you review the steps on:
http://vems.hu/vt/help/main/aim.html ?
If you want to connect the round to your v3 (after the initial setup of both) make sure you use a null-modem cable (cable with 2 male dsub-9 plugs but with swapped tx and rx on both sides, so dsub-9#1 pin 2 connects to dsub-9#2 pin 3, dsub-9#1 pin 3 connects to dsub-9#2 pin 2 and dsub-9#1 pin 5 connects to dsub-9#2 pin 5).
Best regards, Dave