You cannot use the Multiplex Bus Lock option with newer devices such as the DS7432, DS7457i, DS7460i, and the DS7465i.
If the Bus Lock is enabled, it cannot program this code into the newer devices. This causes a data lock on the multiplex bus, and causes the voltage to go from 8.5 Vdc to 12 Vdc. All devices appear missing.
You must disable Bus Lock:
Enter into Programmer's Mode.
Enter the program code (the default program code is 9876).
Press and hold [*] for three seconds to exit Programmer's Mode.