wndr3800 serial port

[shuttrmn]

I understand the need for a ttl converter when connecting my routers serial port to a pc, but is it necessary when connecting to viewsat stb from the 3800's serial port? It is ttl 3.3v. I dont know, and cant find the viewsats rs232 output voltage. The box comes with a null modem cable and the maxttl-rs232 is connected to vcc,tx,rx,grnd, and has a female db9 connector. When I cd into root the software Im running in my router is functioning fine and ready for requests from the box but I can get no further. Thanks for any help.