---
title: "Characteristics of a data logger"
subject: "Instrumentation II"
chapter: 5
key: "semester_5/instrumentation_ii:dl-characteristics"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/dl-characteristics
site: BCT Engineering
---

# Characteristics of a data logger

Instrumentation II · Chapter 5: Data Acquisition And Transmission

- Asked in: 2073 Chaitra, 4 marks; 2071 Shrawan, 5 marks; 2069 Chaitra, 1+3 marks; 2079 Baisakh, 4 marks; 2072 Chaitra, 3 marks; 2075 Asoj, 4 marks (asked 6 times)
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/dl-characteristics
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-5

## Question

What is a data logger? Explain the characteristics of a data logger.

## Short answer

A data logger is an instrument that automatically records sensor data against time. Key characteristics include number of channels, input types, resolution, sampling rate, memory capacity, real-time clock, power options, communication interfaces, and environmental ruggedness.

## Answer

A **data logger** is an instrument that automatically measures and records data from sensors against time, usually in non-volatile memory, for later transfer and analysis; it may operate unattended and stand-alone.

#### Characteristics of a data logger
1. **Number of channels:** from one to hundreds of analog and digital inputs, with a multiplexer.
2. **Input types and range:** thermocouple, RTD, voltage (mV to 10 V), current (4-20 mA), pulse; programmable gain.
3. **Resolution and accuracy:** ADC of 12-24 bits; accuracy depends on the signal conditioner and the ADC.
4. **Sampling rate:** programmable from a sample per day to thousands of samples per second; scan rate per channel.
5. **Memory capacity:** non-volatile flash, SD card; number of records and circular/linear logging.
6. **Real-time clock:** time stamping of data with accuracy and battery backup.
7. **Power:** low power, battery operated, mains with backup; long life.
8. **Communication:** USB, RS-232/485, Ethernet, wireless (Bluetooth, GSM) for download and remote access.
9. **Alarms and display:** limit alarms, status LEDs, LCD.
10. **Software:** setup, graphing, analysis and export (CSV).
11. **Ruggedness and size:** environmental protection (IP rating), temperature range, portable or compact.
12. **Trigger modes:** start/stop by time, level or event; programmable.
13. **Isolation and noise rejection** between channels and from ground.

## Check yourself

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

1. What does a data logger do?
   A. Automatically measures and records sensor data against time, usually in non-volatile memory
   B. Only displays live readings without keeping a record
   C. Controls actuators using feedback from sensors
   D. Amplifies sensor signals for a remote computer
   Answer: A. A data logger records data against time, often unattended, for later transfer and analysis. (Key point: Definition)

2. Why does a data logger have a real-time clock with battery backup?
   A. To set the ADC resolution
   B. To time-stamp each recorded sample accurately
   C. To increase the number of channels
   D. To power the sensors
   Answer: B. The RTC time-stamps data, and the battery keeps time if main power fails. (Key point: Real-time clock)

3. Which statement about the sampling rate of a data logger is correct?
   A. It is fixed at one sample per second
   B. It is set by the sensor type only
   C. It is programmable, from a sample per day to thousands per second
   D. It cannot exceed the number of channels
   Answer: C. Sampling is programmable over a very wide range, and the scan rate applies per channel. (Key point: Sampling rate)

4. Which memory and logging modes are typical in a data logger?
   A. Volatile RAM only, with no logging modes
   B. Magnetic tape with random logging
   C. ROM that cannot be written
   D. Non-volatile flash or SD card with circular or linear logging
   Answer: D. Non-volatile memory keeps data without power; circular logging overwrites the oldest records when full, linear stops. (Key point: Memory and logging)

## Related in Instrumentation II

- [Compact data logger characteristics and block diagram](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acompact-dl-block) — Instrumentation II, chapter 5
- [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×
- [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

## Related in other subjects

- [Short note: Data logger](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Ashort-note-data-logger) — Basic Electronics Engineering, chapter 7, asked 9×
- [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
- [Big data trends, challenges, characteristics](https://www.bctengineer.com/question.md?key=semester_8%2Fbig_data_technologies%3Abig-data-trends-challenges) — Big Data Technologies, chapter 1