What is Data Logger

Physical parameters like humidity, temperature, pressure and water levels are measured and recorded in the data logger. Many data loggers are plug-in boards or use serial communication for connecting to the computer. Some data loggers are standalone devices that do not require a computer for its operation. The data loggers are available in various shapes and sizes with varying signal handling capabilities. The components required for data loggers are as follows:

• Hardware which includes the sensors, signal conditioning hardware and analog to digital conversion hardware.
• A desktop computer
• Data logging software

Working of Data Logger

A sensor is a device which converts one form of energy into another form. Usually, the sensors convert the physical quantities into corresponding electrical signals. The input to the data logger is taken from sensors. These electrical signals, received from sensors, are analog signals and must be converted into digital signals using the analog to digital converter. The digital signal is sampled at a particular rate, where the term sampling rate implies the number of times the signal is measured. The sampling rate must always be greater than the frequency of the original signal. This sampled signal is fed to the computer via a serial port.

Data logger is connected to the computer via serial port. The electrical signals are used by the data logging software that analyzes the signals and stores them. The software used for data logging helps us to configure the time for which the sensors must sense the physical quantities. The data logging software also has an alarm system and a provision to set the sampling rate of the data logger. The procedure of using a data logger is as follows:

• The data logger is fed the input of the sensors like the thermocouple, strain gages and accelerometers.
• The data logging software is configured according to the input sensor selected.
• The parameters like the starting and stopping time and alarms along with other settings are configured using the data logging software.
• Data logging task is started and then the logged data is analyzed and stored using the software.

Data Logger Parameters

Input Signals: The input signal to a data logger is a physical quantity like the temperature, pressure and relative humidity these parameters require different inputs at the data loggers. However, some data loggers have programmable inputs. The programmable inputs offers a provision of using the same input for any kind of physical parameters. Some of the types of physical quantities that can be measured are

• Pressure (barometric, absolute and gauge)
• Pulse (flow and speed)
• Power quality of the voltage disturbances.
• Temperature (zero and extreme hot)

Speed and Memory: The speed of the data logger is determined by the sampling rate of the data logger. The sampling rate of the data logger depends upon the internal memory available. The internal memory available in a data logger is generally low, hence the sampling rate of the logger is less.

Size: The size of the data logger is extremely compact and size can be a critical parameter in various data acquisition systems.

Power: The data loggers are powered externally. Battery powered data loggers are also available.

Real-time Operation: The data is collected in the data logger generally in real time and stored in the computer.

The data loggers are used in various fields like testing of foods and beverages, refrigeration and air conditioning systems, agriculture, aerospace, pharmaceutical and research and development units. The data logger is extensively required in industries for process management, auditing, verification of certain parameters and creating a system profile. The data logger is an essential device in many industries and gives quick and accurate measurement results of various quantities.