Guide to Data Loggers: What is a Data Logger, Types & How it Works?
Data logging means to record events, observations, or measurements systematically. And, the device involved in data logging is known as a data logger. Data loggers come into picture whenever there’s a need to take continuous readings of an instrument. Significantly used in the field of geotechnical instrumentation and monitoring, data loggers are a necessary device.
Here is everything that you would like to know about data loggers — their types, relation with data acquisition system, working principle, specifications, and much more.
What is a Data Logger?
A data logger or a data recorder is an electronic device or a computer program that continuously records data over time in relation to the location either using a built-in instrument or through an externally interfaced one.
The data loggers are primarily based on digital processors and usually look similar to a small portable box/case with batteries, wires, internal memory storage, sensors, and a programmable module.
Figure 1: Inside of a Data Logger
A few of the data loggers interface with a PC to show data through a dedicated software while there are some other that connect directly to a device (LCD, PC, Mobile Phone) and show data as a stand-alone device.
Data Loggers are used in geotechnical monitoring and instrumentation on a large scale because they automatically collect real-time data from the sensors and display it over the mobile device. One can leave the data loggers unattended and can still get the complete data anytime they wish to.
What is Data Acquisition
Data Acquisition is a process of sampling the signals and converting them into readable digital numeric values that can be manipulated by a computer. In simpler forms, a DAS/DAQ/Data Acquisition is the process of converting analogue signals into digital ones for further processing.
Any basic data acquisition system would include:
- Sensors — to convert measured physical parameters into electrical signals
- Signal conditioning circuitry — to convert the sensor signals into a convertible form
- Analogue-to-digital converters — to convert conditioned sensor signals to digital (readable) values
Encardio-Rite has a pair of data loggers — Model ESDL-30, ESCL-10VT — Automatic Data Logger for SDI-12 Interface Sensors
What is Data Acquisition System
A simple device that is used to convert the measured physical parameters into digital signals is known as a data acquisition system. The components of a data acquisition system are as follows:
- Physical System: A physical system captures the physical signal from an instrument and sends it further to the transducer sensor. The signal at this point is an analogue signal.
- Transducer Sensor: The physical signal is then converted to a noisy electrical signal.
- Signal Conditioner: This sensor conditions the electrical signal such that it is convertible into a digital form.
- Analogue-Digital Converter: The analogue-to-digital converter is a device that transforms the analogue electrical signals to the digital signals by the sampling process.
The sampled and converted digital signals are sent to the computer so that they are easily readable.
Encardio-Rite deals with highly reliable and accurate Model EDAS-10 Automatic Data Acquisition System.
What is the Difference between Data Logger and Data Acquisition System?
Now, most of you might be confused between a data logger and a data acquisition system. Well, a data logger is a type of data acquisition system but, a data acquisition system is not necessarily a data logger.
Rate of Sampling
Earlier, data loggers were considered as relatively slower devices in terms of sampling rate while the DAQs were considered to have a sampling rate of up to several GHz. But, as the technology has advanced over time, even the data loggers these days have improved.
Stand-Alone or Interfaced
Data Loggers don’t require an external device or PC network for storage as they have their own volatile flash-based internal memory which can store data of several years. A data logger can also log new data while recycling the older one so that it continues to work indefinitely.
On the other hand, data acquisition systems require a direct connection to a PC using standardises buses. A DAQ/DAS system utilises the interfaced PC, a hard disk memory, or a network storage device to store data.
Power Supply
Data Loggers were built portable so that one can carry them to remote locations and log data. And, it’s not possible to get a power source at every remote location. Hence, the data loggers were made battery-operated so that they can continue to work without any need of external power supply.
Whereas, data acquisition systems require a continuous supply of electricity which is why they are mostly installed in labs or test cells. However, data logger and data acquisition systems are different from each other; both of them would become one in the near future.
Block Diagram of a Data Logger
The block diagram of a basic data logger is as shown in the image below:
Figure 2: Block Diagram of a Data Logger
The data logger is connected to geotechnical instruments like tilt meters,..(Read More)
