Data Acquisition PCI Boards

PCI DAQ boards offer various levels of flexibility and feature-sets, usually based on price. Some of the more-exotic features include synchronous I/O, support for a large selection of signal-conditioning and channel-expansion options, DMA bus mastering (for continuous data transfer without consuming valuable CPU time), support for multiple PCI boards in one PC, and 100% digital calibration.

Also look for extensive software support -- the vendor's own software programs usually won't be enough in the real world of data acquisition. Such cross-vendor software includes: VisualBasic, C/C++, ActiveX/COM. LabVIEW, DASYLab, MATLAB, and Linux.

Typical Board Specifications

• Analog Input Channels: 2, 4, 8,  16, 32 ,etc.
• Differential Channels:  Optional
• Digital I/O Channels:  5 - 100 (varies)
• Sampling Frequency: (varies)
• RAM / On-board Memory: (varies)
• Resolution: 16-bit  (varies)
• Accuracy: % FS

Block View Diagram of Typical PCI DAQ Board

Above: a simplified block diagram of DAQ board, such as the one below...

Above: a typical PCI DAQ board (it looks like a sound or video card, and installs the same ways into your PC)

Synchronous I/O for High-Speed Applications — the ability to make analog measurements, read digital inputs, and read counter inputs, while synchronously generating two (and perhaps more) analog outputs. Some DAQ boards require CPU interaction to access I/O other than analog input, making it difficult to generate time-critical analog waveforms. top of page

Signal Input/Output — Some boards, like those from IOTech, simplify I/O by using only one cable and utilizing a single PCI slot. The latching-pin I/O connector contains all analog input channels plus digital I/O lines, counter inputs, timer outputs and analog outputs. top of page

Analog Input — Example: a 16-bit A/D on a DAQ board will be coupled with 16 single-ended, or 8 differential analog inputs. Look for multiple software-programmable ranges which provide, e.g., ±10V to ±156mV full-scale. Each channel should allow software-configurability for a different range, as well as for single-ended or differential bipolar input.
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Bus Mastering — Some pricier boards support bus mastering DMA (direct memory access) which allows analog and digital/counter input data, as well as analog/digital output data to flow between the PC and the DAQ board without consuming valuable CPU time. The drivers supplied with these DAQ boards, as well as other third-party software support including MATLAB, LabVIEW and DASYLab automatically utilize bus mastering to efficiently perform I/O from the PC to the DAQ board.
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