Data logger

The terms data logger and data acquisition are often used interchangeably. However, in an historical context they are quite different instruments. Like squares and rectangles, a data logger is a data acquisition system, but a data acquisition system is not necessarily a data logger. Both are similar in that they digitize continuously variable (analog) information, ultimately for manipulation and interpretation by a computer. But this is where the similarity ends:

• Data loggers typically have slower sample rates. A maximum sample rate of 5 Hz may be considered to be very fast for a data logger, yet exceeding slow for a typical data acquisition system.

• Data loggers imply stand-alone operation, while the typical data acquisition system must remain tethered to a computer to acquire data. This stand-alone aspect of data loggers implies on-board memory that is used to store acquired data. Sometimes this memory is very large to accommodate many days, or even months of unattended recording.

• Given the extended recording times of data loggers, they typically feature a time- and date-stamping mechanism to ensure that each recorded data value is associated with a date and time of acquisition. As such, data loggers typically employ built-in real time clocks.

• The unattended nature of data logger applications implies the need to operate from a DC power source, such as a battery.

Even though data loggers and data acquisition systems overlap in functionality, there are applications where only a data logger will do. Knowing how these instruments differ may make the path to finding a solution much shorter.

External links

• data logger information from DATAQ Instruments