I've never tried communicating with one of these pumps (apart from "Teach and Learn" between pumps)* ... and the only thing I remember about the RS-232 option is that it needs to be enabled via code 251.
* RS-232 has to be turned off (disabled) for "Teach and Learn" using the IrDA ports.
I seem to recall that "Nurse Call" has to be enabled too, again on Code 251.
