---
title: "Short note: Data logger"
subject: "Basic Electronics Engineering"
chapter: 7
key: "semester_2/basic_electronics_engineering:short-note-data-logger"
source: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/short-note-data-logger
site: BCT Engineering
---

# Short note: Data logger

Basic Electronics Engineering · Chapter 7: Application of Electronic System

- Asked in: 2075 Baisakh, 3 marks; 2074 Bhadra, 3 marks; 2073 Magh, 5 marks; 2071 Bhadra, 4 marks; 2070 Bhadra, 5 marks; 2070 Magh, 3 marks; 2069 Poush, 4 marks; 2068 Bhadra, 3 marks; 2068 Magh, 4 marks (asked 9 times)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/short-note-data-logger
- Whole chapter: https://www.bctengineer.com/md/semester_2/basic_electronics_engineering/chapter-7

## Question

Write a short note on data logger.

## Short answer

A data logger automatically measures and records physical quantities (temperature, pressure, etc.) over time using sensors, signal conditioning, ADC, microcontroller and memory. It stores time-stamped data for later analysis, useful in weather stations, industrial monitoring, and unattended data collection.

## Answer

A **data logger** is an electronic instrument that automatically measures and records physical quantities (temperature, pressure, voltage, humidity, etc.) over time, at fixed intervals, and stores them for later analysis. It can work unattended for days or months.

#### Block diagram

```text
 Sensors -> Signal    -> MUX -> S/H -> ADC -> Micro-  -> Memory
 (T, P, V)  conditioner                       controller   |
                                               |  ^        v
                                          Real-time   Display / PC
                                            clock     interface
```

#### Working

1. Sensors (transducers) convert the quantity into electrical signals.
2. Signal conditioning (amplifier, filter) brings the signal to a suitable level.
3. A multiplexer selects one channel at a time, and the ADC converts the analog signal into digital data.
4. The microcontroller adds the time stamp (from the real-time clock) and stores the data in memory (SD card, flash).
5. The data is shown on a display or transferred to a computer (USB, RS-232, wireless) for graphs and reports.

Advantages: accurate, unattended, saves manpower, many channels. Uses: weather stations, industrial process monitoring, laboratory experiments, cold-storage monitoring, environmental and power-system monitoring.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the main feature of a data logger?
   A. It controls a process by feedback to an actuator only
   B. It generates test signals for circuits
   C. It automatically measures and records quantities over time and stores them for later analysis
   D. It amplifies weak signals only
   Answer: C. A data logger records physical quantities at fixed intervals and stores them, often unattended for days or months. (Key point: What a data logger does)

2. Why is a multiplexer placed before the ADC?
   A. To filter noise from the signal
   B. To store the data in memory
   C. To add the time stamp
   D. To connect one channel at a time so a single ADC serves many sensors
   Answer: D. The MUX selects one channel at a time, so one ADC converts all sensor signals in turn. (Key point: Role of MUX and ADC)

3. Which block gives the time information stored with each reading?
   A. Real-time clock, used by the microcontroller
   B. Signal conditioner
   C. Sample and hold
   D. Sensor
   Answer: A. The microcontroller adds a time stamp taken from the real-time clock before storing the data in memory. (Key point: Time stamp)

## Related in Basic Electronics Engineering

- [Block diagram of data logger](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adata-logger-block-diagram) — Basic Electronics Engineering, chapter 7
- [Data logger and remote control block diagrams](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adata-logger-remote-control) — Basic Electronics Engineering, chapter 7

## Related in other subjects

- [Data logger block diagram and operation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Adl-block) — Instrumentation II, chapter 5, asked 6×
- [Characteristics of a data logger](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Adl-characteristics) — Instrumentation II, chapter 5, asked 6×
- [Data logger input scanner and conditioner design](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Adatalogger-three-transducers) — Instrumentation II, chapter 5
- [Data logger with Bluetooth scatternet](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Abt-datalogger-scatternet) — Instrumentation II, chapter 5