Look at the How to Measure Almost Anything Project here. Essentially, this semester, there was a group effort to put together a personal fab instrument. The following is taken from that page.

TK GUI interface for HTMAA by Grace and Lucy

We wrote a preliminary version of the overall TK gui where people can insert their code for each individual function.

11/6/05: We got the work that Tom and Stacy did. We will insert their python code and try to get a nice GUI going for that. In the meantime, it would be really helpful for us if we could get an idea of what some of the inputs and outputs desired are. For the DVM, its pretty clear that we'd like to have an output of blah number. Would it be helpful to display this information in a graph? etc.

The first version of the HTMAA GUI interface is here

DVM Inputs Outputs:

Inputs: no user input, just circuit interface
Outputs: display voltage value

Variable Power:

Inputs: power value desired
Outputs: actual power dissipated? (concurrent use with DVM?)

Continuity Tester:

Inputs: ???
Outputs: ???

Resistance Meter:

Inputs: none
Outputs: Resistance value

Capacitance Meter:

Inputs: none
Outputs: Capacitance value

Logic Analyzer:

Inputs: ???
Outputs: ???

Oscilloscope:

Inputs: Grid size
Outputs: waveform

Function Generator:

Inputs: Waveform desired
Outputs: none