All About Data Loggers

November 11th, 2020:
Data loggers make up an important area of electronic measurement devices. They come in a variety of types, ranging in size, capabilities and pricing and can perform through a broad range of applications. This article is a brief overview of data loggers. We will explain what they are and how to use them. We will also discuss a few points to consider when selecting the proper data logger for your application.

What is a Data Logger?

A data logger, as the name suggests, logs or records data over time. In its most basic form, a data logger includes one or more internal or external sensors for making measurements, an internal memory for storing data and a microprocessor for controlling its operation. More complex data loggers can include additional features such as a LCD display, an input keypad, control functions and communications including e-mail and text messaging. Many data loggers are designed for very specific environments and applications while others are more versatile and can measure several different variables. Some can operate as standalone devices while others must be connected to a computer for configuration and data download. Data loggers also range in complexity, from economical, single channel, fixed function loggers to more powerful programmable units capable of processing multiple inputs.

How are Data Loggers used?

Data Loggers are routinely used in applications that involve continuously monitoring one or more parameters without requiring the operator to be on site. Typical users include energy auditors, facility managers, electrical and environmental consultants, building managers, process engineers, water and wastewater engineers and research scientists.

Data loggers can operate in indoor, outdoor and underwater environments, performing a broad spectrum of tasks. These include:

  • Tracking electricity usage in facilities to define energy profiles and manage peak demand.
  • Monitoring environmental variables such as temperature, humidity, light, sound, wind velocity and more.
  • Analyzing building operations and identifying electrical, mechanical and other performance problems. Data loggers can then be used to evaluate and fine-tune corrective measures taken to address these issues.
  • Monitoring equipment runtimes to ensure efficient operation.
  • Optimizing HVAC system performance.
  • Testing indoor air quality and temperature.
  • Monitoring water usage, pressure, temperature and flow.

Recorded data can then be analyzed, graphed and formatted for presentation or exported to other applications. This requires downloading the data from the instrument to a computer. Data loggers often come with software that enables the user to process downloaded data and perform other tasks. This software also typically provides data graphing, report generation and export. In addition, the software can sometimes include features for configuring the data logger and displaying measurements in real-time.

What are the advantages of using a Data Logger?

The advantages of using data loggers over other types of data recording instruments include their simplicity and ease-of-use. Once configured, they do not need to be connected to a computer to function. Instead, they can run unattended for extended periods of time (up to several months or more), providing a detailed picture of the conditions being monitored. These can be environmental parameters such as air temperature and relative humidity, electrical data such as energy use and harmonics and many others. Recorded data can then be downloaded to a computer for further display and analysis.

How to choose a Data Logger

As mentioned above, data loggers come in a variety of types, sizes, capabilities and sophistication. Therefore, there are a number of factors to consider when deciding which data logger is right for your application and requirements.

  • Data Type: Data Loggers are designed for many different applications. It is therefore essential to select the instrument that is appropriate for the data to be measured.
  • Input Signal: Some Data Loggers are designed for a single input type, such as voltage or current, while others can be configured to accept multiple types of inputs.
  • Number of Channels: Data Loggers are available in both single and multi-channel designs.
  • Size: In many applications, space can be a limitation. In these situations, the size of the Data Logger may be a critical selection parameter.
  • Speed & Memory: The higher the data recording rate, the more memory is required for storing it. Therefore, when selecting a Data Logger, it is important to determine the storage rate and duration, which can be used to calculate the required memory. This is often a determining factor in the overall cost of the system.
  • Real Time Operation: In some applications it may be advantageous to display measurement data on the computer in real time. This allows operators to check the system status while the recording is in progress.
  • Alarms: Alarm functionality is essential for monitoring a parameter that needs to stay within a critical range. For example: temperature in a cold storage facility. Also consider the alarm delivery system, such as e-mail or text messaging.
  • Accuracy: Accuracy specifications vary widely among different types of Data Loggers. Understanding how accurate your measurement must be can help avoid paying for a high-precision instrument you may not need.
  • Location: Consider whether your location requires a Data Logger designed specifically for that type of environment, or whether a more general-purpose instrument will suffice.
  • Downloading Data: Downloading may consist of simply removing the instrument's memory card and inserting it into the computer. In environments where this may be difficult, consider an instrument that can communicate directly to the computer through a medium such as USB cable, wireless Bluetooth or Wi-Fi.

Note: Information taken from an application note courtesy of AEMC Instruments (via the AEMC Instruments Spring 2017 "Watts Current" Technical Bulletin Issue 12). Ram Meter Inc. sells and stocks an assortment of AEMC Instruments data loggers and other products, which can all be found on our website at You can also check out our full selection of other Data Loggers and Recorders.