Page 1202 - The Mechatronics Handbook

48

Computer-Based

Instrumentation

Systems

48.1 The Power of Software
Kris Fuller 48.2 Digitizing the Analog World
National Instruments, Inc. 48.3 A Look Ahead

Today’s computer-based and networked measurement and automation systems contain powerful software
that brings high-performance in a familiar environment. By using these systems, engineers lower their
costs while increasing productivity and create more customized solutions that directly match their needs.
Electrical and electronics test instruments have always borrowed from contemporary technology that
was widely used elsewhere. The jeweled movement of the nineteenth century used in clocks was first
adapted to build analog meters. In the 1930s, when the variable capacitor, variable resistor, and vacuum
tubes began to be widely accepted pieces of the radio, the first electronic instruments were introduced
using the same components. As display technologies were improved for use on the first televisions, oscillo-
scopes and analyzers began using the same technology to display the user’s measurements (see Fig. 48.1).
These first steps toward computer-based instrumentation met significant challenges. Computerized ins-
trument systems of the 1960s required custom hardware interfaces and low-level assembly languages.
The development of standards, such as the introduction in 1976 of the general-purpose interface bus for
instrument-to-computer connections, provided the foundation for revolutionary improvements in the
development and use of computer-based instruments.
Using the general-purpose interface bus, engineers began writing programs, first in BASIC, then C-
based languages, and ultimately graphical development environments, that transformed their computers
into efficient instrument controllers that also had the capability of electronically storing data. In the
1980s, digitizers and computer plug-in boards for data acquisition became widely accepted alternatives
to expensive standalone instruments. With this combination of software and hardware, engineers began
creating “virtual instruments.”
Throughout the 1980s and 1990s, the idea of virtual instruments gained wider acceptance as the power
of desktop computers increased exponentially. First consumer and then corporate demand for faster,
more efficient CPUs, more capable and compact ASICs, faster and larger hard drives, and more capable
interface buses played right into the hands of those designing computer-based instrumentation systems.
Today’s instrumentation systems are being greatly influenced by the personal computer and Internet
revolutions. Personal computers are now equipped with powerful computational engines that can be
combined with software to create a sophisticated measurement instrument. The data that are acquired
by the computer-based instrumentation system can then be easily transferred to anyone anywhere in the
world who is connected to the instrumentation machine via the Internet.

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