NCD Command Tool for dos 

The NCD.EXE allows you to control NCD products directly from a command line interface in DOS. NCD.EXE does NOT require 3rd party tools or components, as it speaks directly to DOS.
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NCD Device Development Lib 

NCD relay controllers allow computer controlled switching from the RS232 serial port of a microcontroller or computer.NCD video switchers allow computer controlled multiplexing of audio or vide signals from the RS232 serial port of your computer.
relay rs232 control controller device driver com port serial port e3c video switcher a/d