---
title: "Compact data logger characteristics and block diagram"
subject: "Instrumentation II"
chapter: 5
key: "semester_5/instrumentation_ii:compact-dl-block"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/compact-dl-block
site: BCT Engineering
---

# Compact data logger characteristics and block diagram

Instrumentation II · Chapter 5: Data Acquisition And Transmission

- Asked in: 2070 Asar, 6 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/compact-dl-block
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-5

## Question

What are the characteristics of Compact data logger? Explain with block diagram.

## Short answer

A compact data logger is a small battery-operated standalone unit with built-in sensors, ADC, microcontroller, real-time clock, and flash memory. It wakes at preset intervals, reads and time-stamps the sensor, stores data, and later transfers to a PC via USB or wireless.

## Answer

A **compact data logger** is a small, stand-alone, battery-powered logger with built-in sensors or inputs, memory and interface, used for measuring temperature, humidity, voltage etc. at remote places.

#### Characteristics
1. **Small size, light weight,** often pocket size and rugged (IP-rated).
2. **Low power,** battery operated for months or years (sleep modes).
3. **Stand-alone operation:** programmed once, runs unattended.
4. **Few channels** (1-8) with built-in sensors or standard inputs.
5. **Non-volatile memory** (flash/EEPROM) for thousands of readings.
6. **Programmable sampling interval** and start/stop triggers.
7. **Real-time clock** for time stamping.
8. **Simple interface:** USB/ serial/ wireless to a PC, with software for graphs and export; optional LCD.
9. **Low cost,** easy to install.

#### Block diagram
```text
 Sensor(s) -> Signal conditioner -> ADC --+
                                           v
 Real time clock ----> Microcontroller <-> Flash memory
 Keys/LED/LCD <------> (with on-chip ADC) --> USB / Serial / BT
                           ^
              Battery + regulator (low power)
```
The microcontroller wakes up at the set interval, reads the sensor through the ADC, stores a time-stamped value in flash, and goes back to sleep. The stored data are read via USB into the PC.

## Check yourself

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

1. What describes a compact data logger?
   A. Small, stand-alone, battery powered with built-in inputs, memory and interface
   B. Large rack mounted with hundreds of channels
   C. Needs a PC connected all the time
   D. Mains-powered only
   Answer: A. It runs unattended at remote places. (Key point: Compact data logger)

2. How does the microcontroller keep power low?
   A. It stays active at full speed
   B. It wakes at the set interval, logs a reading and goes back to sleep
   C. It runs only on mains
   D. It never reads the sensor
   Answer: B. Sleep modes allow months or years on a battery. (Key point: Low power)

3. Which pairing is typical?
   A. Hundreds of channels and volatile RAM
   B. One channel with no memory
   C. Few channels (1-8) and non-volatile flash memory
   D. Thousands of channels and tape
   Answer: C. Compact loggers are small, with flash for thousands of readings. (Key point: Channels and memory)

## Related in Instrumentation II

- [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 with Bluetooth scatternet](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Abt-datalogger-scatternet) — Instrumentation II, chapter 5
- [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
- [Parallel transfer schemes and 8255A block diagram](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aparallel-transfer-8255-block) — Instrumentation II, chapter 2
- [MBI block diagram and basic features](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-block-features) — Instrumentation II, chapter 1, asked 4×

## Related in other subjects

- [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
- [PID controller block diagram, transfer function, characteristics](https://www.bctengineer.com/question.md?key=semester_3%2Fcontrol_systems%3Apid-bd-tf-characteristics) — Control Systems, chapter 7
- [Data acquisition block diagram and DCS advantages](https://www.bctengineer.com/question.md?key=semester_6%2Fdigital_control_system%3Adata-acquisition-advantages) — Digital Control System, chapter 1