Data Loggers: What is it, Types, Applications & How it Works

1. Guide to Data Loggers What is it, Types & How it Works?

2. 1 7 HOW DO YOU RETRIEVE THE DATA? INTRODUCTION 2 8 BLOCK DIAGRAM OF A DATA LOGGER WHAT IS A DATA LOGGER? 3 9 HOW ACCURATE ARE DATA LOGGERS? WHAT ARE THE WORKING MECHANISMS OF DATA LOGGERS? TABLE OF CONTENT 10 4 WHAT IS A DATA LOGGER AND WHAT DOES IT DO? HOW MANY DATA LOGGERS DO I NEED? 5 HOW LONG CAN DATA LOGGERS RECORD? 11 TYPES OF DATA LOGGERS 6 WHERE ALARMS ARE USUALLY SENT?

3. 1 INTRODUCTION 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.

4. 2 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.

5. 2 WHAT IS A DATA LOGGER? 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. 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.

6. 3 HOW ACCURATE ARE DATA LOGGERS? Encardio-Rite’s data loggers are precisely-built and their accuracy ranges from 1-2% to 0.01% full scale. They have a memory capacity of 64MB which is more than enough to store 2 Million data points. A temperature data logger which is designed for warehouse storage temperature monitoring normally has an accuracy of 1-2 °F.

7. 4 HOW MANY DATA LOGGERS DO I NEED? The need for data loggers depends upon the number of measurement points that you have or the number of sensors that you want to connect to it. Data loggers are available in multiple configurations so that you can choose accord- ing to your needs. For instance, the ESCL-10VT data logger is a single channel data logger whereas the ESDL-30 is a multiple channel data logger with 160 inputs.

8. 5 HOW LONG CAN DATA LOGGERS RECORD? The duration of data logging depends upon two parameters – the power backup of the data logger and its memory capacity. While most of the data loggers have high longevity and durability, they continue to operate for many years. The sample rate multiplied by the number of channels being recorded gives the length of time the logger can operate before the memory is filled. Some of the data loggers are programmed to over-write the data once the memory is filled while some of them stop logging data once the memory is full.

9. 6 WHERE ALARMS ARE USUALLY SENT? While monitoring structures like tunnels, dams, high-rise buildings, a certain alert level is pre-determined and, as soon as the deformation or fault reaches beyond that particular level, the data loggers send an emergency alert either through an SMS or an email. There are a few other data loggers that come with in-built LEDs, alarms or buzzers to alert the local persons in case of an emergency.

10. 7 HOW DO YOU RETRIEVE THE DATA? There are two options available for data retrieval and transmission through Encardio’s data loggers: Telemetry through GSM/GPRS modem In an area with GSM/GPRS service, the data from the automatic data logger can be transmitted remotely to a PC at a central location. The user will need to arrange a data SIM card for each data logger. Readout/data retrieval using laptop PC The logged data from the data logger is directly downloaded to a laptop/PC. Data can also be transferred to the central PC or server from the laptop using either a USB pen drive or through the Internet.

11. 8 BLOCK DIAGRAM OF A DATA LOGGER

12. 9 WHAT ARE THE WORKING MECHANISMS OF DATA LOGGERS? Data loggers usually appear like a small box enclosing batteries for power supply, microprocessors, internal memory storage, sensors, and a programmable module. Encardio-Rite has two models of data loggers i.e. ESCL-10VT and ESDL-30. The ESCL-10VT is a single channel data logger for vibrating wire sensors which means, it can be directly connected to vibrating wire sensors such as piezometers, strain gauges, extensometers etc. ESDL-30 is an automatic data logger that uses SDI-12 interface to connect with the sensors. Once the sensors are connected to the data loggers, the data through these sensors is logged at regular intervals by the data loggers and stored in its internal non-vola- tile memory.

13. 9 WHAT ARE THE WORKING MECHANISMS OF DATA LOGGERS? The users can retrieve this data remotely over their mobile device using Encardio’s cloud service. While monitoring of the structures, a certain alert level is pre-set. If the data logged is beyond the alert levels, an email or SMS emergency alert is sent to the user so that preventive measures can be taken before any mishap or accident.

14. 10 WHAT IS A DATA LOGGER AND WHAT DOES IT DO? Data Loggers are simply yet significant sensors having a wide range of application in the field of geotechnical monitoring and instrumentation. Some of its applications include: • • • Comprehensive tunnel monitoring for the long-term safety of the tunnel, to study the behaviour of the tunnel over the time, especially with respect to the rheological behaviour of the rock mass and obvious changes in the fault zones, walled sections, inflow, etc. Structural health monitoring of existing buildings to keep track of the building’s performance over time and effect of nearby construction or excavation. Data loggers create an early warning in case of emergency so that the user can take preventive measures. Landslide monitoring to avoid mishaps and create early warnings so that loss of life and property can be prevented.

15. 10 WHAT IS A DATA LOGGER AND WHAT DOES IT DO? • • • • • Groundwater monitoring and rainfall management so that the most important freshwater resource can be saved from depleting and there’s an even distribution of the resource among all. Monitoring deformation of land and surrounding areas during deep excavations. Excavation in soft ground induces ground movement which imposes a threat to nearby sensitive structures in the zone of influence. Hence, deep excavation risk assessment and foundation crack monitoring are crucial at all the levels. Monitoring of deformities in bridges so that early warning can be generated in case of an emergency Unattended dam and nuclear power plant monitoring to avoid fatal accidents. Data loggers log data from different sensors and send it to user’s remote device. Unattended weather changing parameters recording through weather stations to aid in agricultural activities. https://www.encardio.com/geotechnical-instruments/extensometers/

16. 11 TYPES OF DATA LOGGERS Model ESDL-30 Automatic Data Logger for SDI-12 Interface Sensors Encardio-Rite Model ESDL-30 data logger is designed to log data from sensors with SDI-12 interface. Any sensor with an SDI-12 signal interface can be connected to the data logger e.g. based on vibrating wire, resistance strain gauge or MEMS technology etc.

17. 11 TYPES OF DATA LOGGERS ESDL-30 can be used to connect a large number of sensors with the SDI-12 interface. The data recorder is fully compatible with all measurement commands signal as per SDI-12 standard. They can be programmed to take a measurement between a range of 5 seconds to 168 hours in linear mode. SDI-12 is a multi-drop interface that can communicate with multi-parameter sensors. All the measured data is stored, together with the current date, time and battery voltage, as a data record in the internal non-volatile memory of the logging device.

18. 11 TYPES OF DATA LOGGERS Model ESCL-10VT Single Channel Data Logger for Vibrating Wire Sensors The Model ESCL-10VT is a single channel vibrating wire data logger, designed for monitoring a single vibrating wire sensor.

19. 11 WHAT ARE THE TYPES OF EXTENSOMETERS? TYPES OF DATA LOGGERS This data logger uses a Bluetooth modem to interface with the mobile phone. The data logger can be connected through a mobile phone using ESCL-10VT application software. The data logger can additionally monitor barometric pressure and rainfall, using a tipping bucket rain gauge.The Model ESCL-10VT-BX data logger can be programmed to take a measurement from 5 seconds to 168 hours in linear mode. It has Windows-based application software with features that allow the user to set the sensor calibration coefficients, recording intervals, data logger or borehole code (identification tag numbers), sensor serial number, real-time clock time etc. of the data logger conveniently. The user can monitor readings and GPRS signal strength for diagnostic purpose. User can also start or stop, scan, or manage data files, download data from the data logger, perform data correction, save and export the data files.

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