From Measurement Systems and Sensors

11.1 COMPUTER DAQ BOARDS

11.1.1 Structure and Functions of a DAQ Board

Certain measurement tasks cannot be performed better than by means of a computer measurement board. Combined with a computer and software, such measurement boards makes up a virtual instrument. Due to its extensive data acquisition functionality, a computer measurement board is referred to as Data Acquisition (DAQ) card. Card designations often include additional symbols DAQBoard designates a board that is designed for installation inside a computer (pluggable onto the PCI or ISA bus); and DAQ PCcard designates a PCMCIA card. The functions of a measurement card involve much more than just A/D conversion [1, 2]. Modern computer DAQ boards provide the following functions:

  • Digitize a single signal (voltage or sometimes current) from one of the multiple analog inputs;

  • Digitize multiple signals received on multiple analog inputs;

  • Perform antialiasing analog filtration of the input signal;

  • Set the analog input signal trigger levels and time-outs;

  • Present the required signals (voltage or current) onto analog outputs through D/A conversion;

  • Read and send digital signals from/to data inputs/outputs (DIO);

  • Produce signals of a preset frequency or pulses of a preset duration;

  • Measure the input signal frequency or pulse duration;

  • Synchronize with the triggering lines of computer-based RTSI real-time systems (optional);

  • Store measurement data and configuration settings in the card's memory.

Figure 11.1 shows a functional diagram of a DAQ board. A typical DAQ board consists of an analog multiplexer, a programmable amplifier, a sample-and-hold (S&H) or sample-and-trace (S&T) circuit, an ADC, a DAC,...

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Products & Services
Data Acquisition Computer Boards
Data acquisition computer boards are self-contained printed circuit boards that typically plug into the backplane, motherboard, or otherwise interface directly with the computer bus.
Data Acquisition
Data acquisition is the digitizing and processing of multiple sensor or signal inputs for the purpose of monitoring, analyzing and/or controlling systems and processes. Signal conditioning includes the amplification, filtering, converting, and other processes required to make sensor output suitable for rereading by computer boards.
Data Acquisition Software
Data acquisition software is designed to collect, record, store, present and analyze data collected from sensors and other digital devices.
Data Acquisition Systems and Instruments
Data acquisition systems and instruments collect, digitize, and process multiple sensor or signal inputs for the purpose of monitoring, analyzing and/or controlling systems and processes.
Signal Conditioners
Signal conditioners provide amplification, filtering, converting, and other processes required to make sensor output suitable for reading by computer boards.

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