A data logger (also datalogger or Data recorder) is an electronic device that records data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor (or computer). They generally are small, battery powered and portable.
Basically three types of instruments are commonly used for collecting and storing data. They are
1) Real-Time Data Acquisition Systems
2) Chart Recorders and
3)Dataloggers
Data loggers are normally more economical than chart recorders. They offer more flexibility and are available with a greater variety of input types. Most data loggers collect data which may be directly transferred to a computer. Although this option is available with some recorders, it normally adds significant expense to the recorder price.
Data acquisition systems offer a great deal of flexibility and are certainly attractive when high sample rates are required, however, since they require connection or installation into a computer, the computer must also be present and active when collecting the data. Data loggers can collect data independently of a computer. Data is normally collected in non-volatile memory for later download to a computer. The computer does not need to be present during the data collection process. This makes them ideally suited for applications requiring portability.
Data loggers vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment only. It is common for general purpose types to be programmable however many remain as static machines with only a limited number of changeable parameters.
The recording duration is dependent on the memory capacity of the data logger and the desired sample rate. To determine the duration divide the memory capacity (number of samples the device can record) by the sample rate. As an example assume that a given data logger can store 10,000 samples. If it is desired to record 2 samples every minute, the data logger can run for 10,000/2 or 5,000 minutes (about 3.5 days). If the sample rate was cut in half (1 sample per minute), the recording period would double to 7 days.
1.1 Data logger Types:
a. Miniature Single Input Data Loggers:
Miniature single input data loggers are generally low cost loggers dedicated to a specific input type. These types of data loggers are often used in the transportation industry. A typical application would be to include a temperature data logger in a shipment of food products to insure that the food temperature does not exceed acceptable limits.
In addition to temperature miniature data loggers are available for a large variety of input types.
b. Fixed
Fixed input loggers have a fixed number of input channels which are generally dedicated for a specific type of input. OMEGA offers fixed input data loggers ranging from one to 8 channels.
c. Handheld Multi-Channel Data Loggers:
Handheld multi-channel loggers are commonly used in applications where the data logger is to be carried from one location to another.
They are also commonly used in benchtop or laboratory environments. In addition to storing data internally some models even contain on board printers which can produce an immediate hardcopy of the data.
d. Modular Data Loggers:
A modular data logger is configurable and expandable through the use of plug-in modules. The modules are normally field configurable and the user has the option of adding as many channels to satisfy the application requirement.
