What is a Data Logger?

HVAC Monitoring

A data logger, often referred to as a “HOBO,” is an electronic instrument that records measurements at set intervals over a period of time. Depending on the particular data logger, such measurements can include: air temperature, relative humidity, AC/DC current and voltage, differential pressure, time-of-use (lights, motors, etc.), light intensity, water temperature, water level, dissolved oxygen, soil moisture, rainfall, wind speed and direction, leaf wetness, pulse signals, room occupancy, plug load, and many more.

Data loggers are typically compact, battery-powered devices equipped with an internal microprocessor, data storage, and one or more sensors. They can be deployed indoors, outdoors, and underwater, and can record data for up to months at a time, unattended. A data logger may be a single-unit, stand-alone device with internal sensors, which fits in the palm of a hand, or it may be a multi-channel data collection instrument equipped with one or more external sensors. 

How does a data logger work?

First, the data logger is connected to a computer via a USB interface. Next, accompanying data logger software is used to select logging parameters (sampling intervals, start time, etc.) and activate the logger. The logger is then disconnected and deployed in the desired location, where it records each measurement and stores it in memory along with the time and date. Bluetooth Smart loggers can be configured and launched wirelessly, after deployment. 

After the desired monitoring period, the data logger is then reconnected to the computer and the software is used again to read out the data and display the measurements in graphs that show profiles over time. Tabular data can be viewed as well, or exported to a spreadsheet for further manipulation.

In the case of web-based data logging systems, data are pushed to the Internet for access; with wireless data nodes, data are transmitted to a central receiver; and with Bluetooth Smart loggers, data are downloaded directly to your mobile device.

Where are data loggers used?

Data loggers are used in a broad range of indoor, outdoor and underwater environments – essentially anywhere data is needed and the convenience of battery power is preferred.

Datalogger Usage

What are the different types of data loggers?

Datalogger types

The four main types of data loggers include stand-alone data loggers, web-based data logging systems, wireless data nodes, and Bluetooth Smart data loggers. 

Stand-alone USB data loggers are compact, reusable, and portable, and offer low cost and easy setup and deployment. Internal-sensor models are used for monitoring at the logger location, while external-sensor models (with flexible input channels for a range of external sensors) can be used for monitoring at some distance from the logger. Most stand-alone loggers communicate with a computer via a USB interface. For greater convenience, a data shuttle device can be used to offload data from the logger for transport back to a computer.

Web-based data logging systems enable remote, around-the-clock Internet-based access to data via GSM cellular, WI-FI, or Ethernet communications. These systems can be configured with a variety of external plug-in sensors and transmit collected data to a secure web server for accessing the data.

Wireless data nodes transmit real-time data from dozens of points to a central computer, eliminating the need to manually retrieve and offload data from individual data loggers.

Bluetooth Smart enabled data loggers measure and transmit temperature and relative humidity data wirelessly to mobile devices over a 100-foot range.