The data acquisition card is a piece of test equipment that is in the form of a circuit card rather than being self-contained in its own enclosure and using a familiar interfacing scheme such as PCI, USB, wireless, ISA, PCMCIA, Serial i/o or GPIB. Data acquisition (DAQ) cards allow you to save money on test equipment by repurposing your computer to do the same job. Also, shelving space is saved due to the equipment you won't have to keep handy in your lab.

Some of the high-performance DAQs that are available will perform a range of test, measurement and control functions. In concert with well-written software, a DAQ card will transform a personal computer into a powerful measurement system. You can do automated testing and experimentation and you can monitor and/or control production line equipment. You can even link in to auto testing simulators or medical monitoring devices. When you search a data acquisition card directory:

1. Locate DAQ cards designed for a PCI slot.

2. Consider buying a fully integrated high-performance DAQ card system.

3. Acquire a DAQ card designed to work with a laptop.

Action Steps
The best contacts and resources to help you get it done

Acquire a DAQ card configured for a personal computer

A personal computer is the most common venue for a DAQ card. Cards are available covering areas such as digital multimeter functionality, high-speed digital i/o, and temperature. Ask your data acquisition card provider either for 12-bit or 16-bit DAQ cards, depending on the accuracy you require.

I recommend: Omega and IOtech both have a broad list of data acquisition cards covering both electrical and temperature measurements. Signatec has some very high-level systems on DAQ cards.

Get a fully integrated system with more than one DAQ card

These products can be interconnected through a high-speed bus for real-time applications. These are specially designed high-performance systems that can contain multiple DAQ cards for maximum performance. They also typically come with software that will operate the various boards at either the board level or at the system level. Unlike a PC-based DAQ system, these fully integrated systems are ready to go, out of the box.

I recommend: Signatec carries a fully integrated DAQ system that houses multiple DAQ boards for applications in signal analysis. Microstar Laboratories has some impressive offerings in this category.

Find data acquisition card products for your laptop computer

Data Acquisition Card information would not be complete without mentioning DAQ cards for notebook computers. The cards use the PCMCIA interface and are smaller than the PCI cards, but they're just as functional.

I recommend: SuperLogics has an impressive PCMCIA data acquisition card list. Hacker has numerous PCMCIA DAQ cards for both electrical measurements and for communications. Janbit weighs in with a list of analog and digital electrical measurement DAQ cards with accuracy choices of 12-bit and 16-bit.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Remember to do the following when making DAQ card measurements: try to eliminate DC common mode voltage; try to eliminate AC common mode voltage; break any ground loops; use 4-20 mA loop currents; and use 24-volt digital logic.