New to using serial console and trying to log into embedded system

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http://unix.stackexchange.com – I have two PC Engines Alix 2d2 which I've been given and I'm trying to install an (BSD or Linux based) OS on. Currently one has a version of openWRT (the other had openWRT until I formatted the CF card and put on a version of FreeDOS (I don't know if this works because no console)). Both boards were in working order before I began, allbeit working as openWRT systems. I did not test either of their serial ports before I started (although i have changed nothing about the second system so...) In addition to the alix boards I have a Windows desktop which has a USB to serial adapter, 1 serial cabl (HowTos)