Real World Instrumentation with Python

Chapter 14. Real World Examples

Beware of computer programmers who carry screwdrivers.

—Leonard Brandwein

This chapter is intended to be a summarization of some of what I’ve presented in this book, so it’s not going to contain a lot of in-depth discussions. Rather than a step-by-step analysis and guide, it’s intended to be an inspiration for your own problem solving. You should be able to answer most questions that arise regarding the examples in this chapter by referring to the material we’ve covered in the preceding chapters, and if you need more details than can be found here you can look to the references and links provided in the chapters and the appendixes.

As you have probably surmised by this point, there are basically two main classes of instrumentation interfaces: those that require some type of add-on hardware that plugs into a computer, and those that require only a cable of some type. In this chapter we will wrap up our journey by examining examples of those devices that require only a cable. Drawing from what we’ve seen so far, we will see how RS-232 serial and USB interfaces can be used to acquire data and control devices in the real world.

We’ll start off with a data capture application for a DMM with a serial output (the same one we discussed briefly in Chapter 11), and then look at some other types of serial interface I/O devices that employ a more conventional command-response protocol. Next up is a USB data acquisition and control device, the LabJack U3. We’ll spend ...