Page 1160 - The Mechatronics Handbook

FIGURE 44.3
precise, it could still be inaccurate if the readings were consistent but significantly different than the
actual value of the signal.
The accuracy of a data acquisition system can change with temperature, time, and usage. Data acqui-
sition hardware can store on-board correction constants for offset and gain errors. An offset error is a
constant difference between the measured and actual voltage, regardless of the voltage level. A gain error
increases linearly as the measured voltage increases. Some data acquisition hardware also include an
accurate voltage source on-board that can be periodically used as a reference to correct the gain and
offset error parameters.
The final piece of a data acquisition system to understand is the software. The driver software is a set
of commands that a programmer can incorporate into a program. The driver software is usually supplied
by the manufacturer of the hardware and can be used in a variety of programming languages. A pro-
grammer can use a programming language to build an application from the driver software like the one
in Fig. 44.3. The application is then ready for an end user to easily control and acquire data from the
hardware—a custom instrument built specifically for the user’s needs.

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