The PC is now an economic and common equipment at home or office. To interface it to the real world is a step in learning Automation and Robotics. In Automation we have both Industrial and Home.
Experimenting with Home Automation and Building PC based Instruments is the first step. An Electronics card needs to be interfaced by Serial, Parallel or USB Ports.
Some Small VB6 Software Source for Virtual Electronic Instruments are available here for Learning and Developing.
You can Read More about it at my Data Interface Circuits section Computer Data Interface
These Programs use a component Inpout32.dll from Inpout32.dll from Logix4u, Obtain the Source code and License.
These Programs are for Experimentation and Educational purpose, Not Suitable for Commercial Applications. The Orcad 9 Student Edition Design Source also given here.
Project Source – virtual-instrumentation – Examples of Computer Interface to Instruments
These are the Theory and Description Pages for the VB Programs with circuits in this project.