What is a Data Logger?

HVAC Monitoring

A data logger (or datalogger), commonly referred to as a “HOBO,” is defined as an electronic instrument that records measurements of all types at set intervals over a period of time.

Data loggers can record a wide variety of energy and environmental measurements including temperature, relative humidity, AC/DC current and voltage, differential pressure, time-of-use (lights and motors), light intensity, water level, soil moisture, rainfall, wind speed and direction, pulse signals, and more.

Typically, data loggers are compact, battery-powered devices equipped with an internal microprocessor, data storage, and one or more sensors.

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Using a Data Logger - 5 Easy Steps

How does a data logger work?

First, the data logger is connected to a PC or MAC computer via a USB interface. 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.

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, and with wireless data nodes, data are transmitted to a central receiver.

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
From left to right: Standalone HOBO U12 temp/RH, Web based HOBO U30 data logging system, and wireless HOBO ZW data node

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

Stand-alone 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 PC or Mac 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 access to data via GSM cellular, WI-FI, or Ethernet communications. These systems can be configured with a variety of externalplug-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 PC, eliminating the need to manually retrieve and offload data from individual data loggers.