Franco;
That board of yours has two different handshake lines, meaning that you can have two different groups doing a different task.
There is a valid combination of port numbers and group numbers when you are using more than one port per group (that board has a total of 4 ports of 8 bits each).
The best resource for you is the board Users Manual. You will find the table with the legal combination of port numbers and groups.
To accomplish you particular application, you can open the Labview shipping examples or the NI-DAQ shipping examples, that show the pattern input and pattern output tasks; then configure each example to execute in a different group and both groups to have 2 ports each (based upon the legal combination of ports and groups from the Users
Manual).
After that you should be set to go.
Hope this helps.
Filipe