Hi Noely,
I found the following website which looks at the general specifications of a serial network.
http://www.lammertbies.nl/comm/info/RS-232_specs.html
This shows lots of general information about serial networks, controlling a serial network with NI kit will have the same specifications as any other serial network. What other starting points are you looking for? If you have some specific questions then I would be more than happy to look into them for you.
Best regards,
Peter H.
Applications Engineer.
NIUK.