Data logger is a broad term that may refer to any device that stores sensor measurement data. Many smart sensors integrate on-board data logging electronics. However, for the purposes of environmental data logging, systems typically include dedicated data logger units that can interface with multiple sensor types and, in many cases, transmit the data.
Data loggers serve as the backbone of environmental monitoring systems, capturing data from connected sensors over time. They range from simple, single-channel units to complex arrays capable of handling numerous inputs and outputs. While the primary role of data loggers is to store and transfer data, they may also be equipped with relays and other functions that allow them to interface with and control other devices.
Data Logger Features
Some of the features typical of environmental data loggers include:
- Sensor Inputs: Also referred to as ports or channels, these are the interfaces that allow sensors to be connected either by connecting bare wires to a terminal or through pluggable sensor connectors.
- Internal Memory: Data loggers typically feature a non-volatile (not erased when powered off) memory for storing configuration settings and dedicated memory for storing sensor data such as flash memory or an SD card.
A sensor with an internal memory will store data throughout the duration of the deployment.
- Rugged Housing: Given that data loggers are often used in harsh environments, they often include ruggedized enclosures with an IP (Ingress Protection) rating indicating their resistance to dust and water intrusion1.
- User Interface: Data loggers feature one or more interface options for configuration and data download, such as a USB connection to a field computer running software, Bluetooth connection to a mobile app, or a display screen.
- Power Management: Since many environmental loggers operate from solar-charged batteries, they often include power-efficient electronics and features like switch power to reduce consumption by turning off devices between measurement cycles.
- Real-time Data Transmission: Many loggers offer telemetry options such as cellular, satellite, radio, or Wi-Fi to transmit data in real-time for immediate analysis and response.
Each logger will vary in some ways and may offer different sets of advanced features, but these are some of the commonalities to the majority of data loggers designed for environmental data logging.
How is Data Acquired from Loggers
Data logging systems can be broadly categorized into two primary types based on their connectivity and data transmission capabilities: direct connect and telemetry systems.
Direct connect data loggers are designed for situations where data can be manually retrieved from the device, or where it is possible to feed a direct cabled connection into a data management system. In a standalone configuration, these systems store data internally, which can later be downloaded via a direct connection to a computer or mobile device.
A primary advantage of direct connect systems is that they are often less expensive and complex than telemetry systems due to the absence of wireless communication hardware. They are ideal for locations where periodic visits for data retrieval are feasible, such as research sites, controlled environments, or smaller-scale monitoring projects.
Telemetry data loggers are equipped with wireless communication capabilities that allow for remote data transmission and real-time monitoring. While more expensive and complex to commission, telemetry loggers offer the benefits of remote data acquisition, configuration, and troubleshooting that can minimize the need for site visits.
Telemetry systems are ideal for remote or difficult-to-access locations and situations where continuous, real-time data is essential, such as flood monitoring and environmental compliance.
Telemetry systems will be explored in greater depth in the Telemetry chapter.
A telemetry unit like the NexSens X3 data logger transfers data to the cloud, where it can be viewed remotely in real-time.
Conclusion
Data loggers are at the core of environmental monitoring systems, offering versatile and reliable means to collect, store, and transmit data from various sensors. With their robust storage capabilities and advanced features like real-time data transmission, they are essential for effective environmental data collection and management, providing the critical data needed to understand and manage the natural environment.
Resources
- International Electrotechnical Commission. (n.d.). Ingress Protection (IP) ratings. Retrieved June 15, 2024, from https://www.iec.ch/ip-ratings