Page 1226 - The Mechatronics Handbook

FIGURE 50.3 Measurement hardware components of PC-based data-logging system.

FIGURE 50.4 Examples of signal connectivity options.
system, are the most basic form of connectivity. Screw terminals are a good choice for general-purpose
use, particularly when you need to connect a large number of signals into a small amount of space. The
disadvantage of screw terminals is that they are time consuming to connect and difficult to reconfigure.
Figure 50.4 shows some other standard connectivity options that are designed to make connecting and
disconnecting sensors less labor-intensive. Minithermocouple connectors are a widely used connectivity
option for thermocouples. BNC and SMB connectors are commonly used when electrical shielding is
required for noise immunity. Banana jacks are often used when measuring current, resistance, or higher
voltages. The sensor provider typically defines the connectivity options available for a sensor, and it is
up to you to choose measurement hardware that can accept that connectivity.

Signal Conditioning
Signal conditioning is one of the most important and most overlooked components of a PC-based data-
logging system. Many sensors require special signal conditioning technology. For example, signals from a
thermocouple are very low voltage and require amplification, filtering, and linearization. Other sensors,
like strain gauges and accelerometers, require power in addition to amplification and filtering, while other
signals may require isolation to protect the system from high voltages. No single stand-alone datalogger
can provide the flexibility required to make all of these measurements. However, with front-end signal
conditioning, you can combine the necessary technologies to bring these various types of signals into a
single PC-based data-logging system.

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