Question

In this section, we look at transmission of ASCII characters using (RS-232) binary asynchronous serial format Given a digital multi-meter and an RS-232 cable, describe the measurements you make to determine whether the cable is a NULL modem cable or not a.

Answer 1

Connect and hold one end of the multimeter probe on pin 1 of the cable.
Connect and hold the other end of multimeter probe on pin 1 of the other end of the cable.
If the beep sound comes from the multimeter then there is continuity in the cable.
If it does not beep then the connection for that set of pins must be repaired.