Data Acquisition Categories
Data Acquisition FAQs
"What is data acquisition?" and other questions are explained in this data acquisition FAQ.
- What is data acquisition?
- What is a data acquisition system?
- What are different types of data acquisition systems?
- What is a general-purpose data acquisition device?
- What is ADC Measurement Resolution?
- What is the Sample Rate of a Data Acquisition System?
- What is an isolated data acquisition unit?
- Are data acquisition products calibrated?
- What software is available for data acquisition systems?
- What operating system is required?
- Can I write my own data acquisition application?
- Can a data acquisition system operate without a connected PC?
- What data storage format should I use?
Data acquisition is the process of storing information from electrical signals measuring real world physical conditions (like voltage, current, temperature, and strain), converting the samples to digital values using an analog-to-digital converter, and saving the digitized samples to either a connected computer or to an on-board memory device. This saved data can then be manipulated by a computer for analysis. Read the article What is Data Acquisition and Why is it Important? for more information.
A data acquisition system may include sensors, a data acquisition device to receive and record the sensor signals, and software to analyze the signals acquired.
There are a multitude of distinguishing characteristics that can define a data acquisition system. The type of measurement or measurements the device can measure (analog or digital), the communications interface (USB or Ethernet), the type of data storage used (on-board memeory, PC-based, removable flash memory), if the device channels are isolated, and many more. Some data acquisition systems are specific to an application. For example, temperature monitoring in cold-chain goods. However, there are many general-purpose data acquisition systems to accommodate a multitude of signals and applications.
A general-purpose data acquisition system can accommodate multiple types of applications and measurements using software to specify and setup acquisition for a particular goal.
The ADC (analog to digital converter) measurement resolution refers directly to the bit value of an analog-to-digital converter. This value determines how finely it slices its full-scale measurement range (i.e., the smallest change in the input signal that it can theoretically measure). This value is calculated by dividing the full scale range with the ADC Resolution. For example, a 12-bit device with a full scale measurement range of ±10V can detect a change in voltage as low as 0.0048828125 Volts (20/4069=0.0048828125). Read the article How Much ADC Resolution Do You Really Need? to learn more.
Sample rate is the number of data samples taken over a given period of time. Sampling rate (or sampling interval) is purely product-dependent. Some devices can record one sample per hour while others can record 160,000 samples a second or even faster. Choosing the right sample rate at which to record data can sometimes be a complex issue to resolve. Read the article What You Really Need to Know About Sample Rate to learn more.
Electrical isolation is a protective design feature used to separate measurement signals from each other in order to keep them from interacting. Use isolated instruments to eliminate ground loops, isolate signals, and minimize noise.
All data acquisition systems are calibrated at the factory. NIST-traceable calibration certificates are available and provided with many instruments. Yearly recalibration services are available.
Software support is different depending upon the product. All Dataq Instruments data acquisition products provide free WinDaq Data Acquisition Software Suite that includes recording and playback and analysis software. Other products generally include a free utility to allow setup and data viewing.
Dataq Instruments WinDaq software is a Windows application. Applications in other operating systems may be built using the device's published protocol.
Dataq Instruments data acquisition products provide a published protocol as well as a .NET class and SDK for programming in any language. Visit our Github page for sample programs.
Many data acquisition products can operate without a PC recording data to removable flash memory, internal memory, or the cloud.
Only a handful of products are provided with software that allows you to define the storage format. Some products record data only in a text file format, and others only in a binary format (for example, WinDaq). Products in the latter category will always provide software to convert all or part of a binary data file into text suitable for importing into most applications, the most notable of which is Excel. However, note that a binary data file or segment that is converted into a text format will explode in size by at least a factor of ten. Only two bytes are required to represent an acquired value in binary. The equivalent value in a text format is a function of the number of digits of precision, a decimal point, a delimiter, and line terminators. Binary is always a more memory-efficient storage format than text. This may become important as sampling rate and record times increase.