When you are using hyperterminal, what kind of cable are you using? Is it straight or null? When you try with RTI, do you attach that same exact cable to the end of your CM-232? If not, I suggest starting there. Since you mentioned the RJ-45 to DB-9, is it safe to assume the preamp has an RJ-45 serial connection? If not, dump that adapter. Let us know how it works for you. Good luck!