---
title: "Microprocessors in instrumentation systems (case study)"
subject: "Instrumentation II"
chapter: 1
key: "semester_5/instrumentation_ii:mbi-casestudy-statement"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/mbi-casestudy-statement
site: BCT Engineering
---

# Microprocessors in instrumentation systems (case study)

Instrumentation II · Chapter 1: Microprocessor Based Instrumentation System

- Asked in: 2072 Kartik, 4 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/mbi-casestudy-statement
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-1

## Question

"Microprocessors are indispensable tools in modern industrial instrumentation systems". As an engineer, provide a technical explanation including block diagrams to this statement by relying on observations from your case-study.

## Short answer

A microprocessor-based boiler temperature system digitizes the thermocouple, linearizes it, runs PID, drives a valve via DAC, and handles alarms, display, logging. Software changes modify control, so it is indispensable for flexible, accurate automation.

## Answer

Modern industry needs automatic measurement, decision and control of many variables with accuracy and speed. A microprocessor gives programmable intelligence at low cost, so it is the heart of today's instrumentation.

#### Case study: boiler (furnace) temperature control in a plant
A thermocouple measures boiler temperature. The signal is amplified, cold-junction compensated and digitised by an ADC. The microprocessor linearises it, compares it with the set point (say 400 deg C), runs a PID algorithm and drives a fuel valve through a DAC. It displays the value, logs it and raises an alarm if the temperature exceeds the limit.

```text
 Thermocouple -> Amplifier -> ADC -> Microprocessor -> DAC -> Valve
       ^                              |   |   |                 |
       |                           Display Alarm PC link        |
       +----------------- Boiler <---------------------------- +
```

#### Observations supporting the statement
1. Control algorithms (PID, limit checks) run in software and are easily tuned.
2. One processor monitors many channels by multiplexing, reducing cost.
3. Accuracy is high: calibration and linearisation are done digitally.
4. Alarms, interlocks and safety shutdown happen automatically and quickly.
5. Data logging and communication (RS-485, Ethernet) allow remote supervision.
6. Changes in process need only software changes.

Therefore the processor is indispensable for modern industrial instrumentation.

## Check yourself

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

1. In the boiler case study, how does the microprocessor control temperature?
   A. Linearises the thermocouple signal, compares with set point, runs PID and drives a fuel valve via DAC
   B. Switches the valve randomly
   C. Only displays the value
   D. Sends the value to the thermocouple
   Answer: A. The loop uses sensing, comparison, PID and DAC to the valve. (Key point: Case study loop)

2. How does one processor monitor many channels?
   A. By using one processor per sensor only
   B. By multiplexing the channels, reducing cost
   C. By ignoring some channels
   D. By using analog meters
   Answer: B. Multiplexing shares the processor and ADC among channels. (Key point: Multiplexing)

3. Which observation supports the statement regarding safety?
   A. Operators must always react manually
   B. Alarms are impossible
   C. Alarms, interlocks and shutdown happen automatically and quickly
   D. Shutdown requires hardware rewiring
   Answer: C. Software triggers fast automatic safety actions. (Key point: Safety)

4. What is needed when the process changes?
   A. Complete hardware redesign
   B. New processor family
   C. Rewiring all sensors
   D. Only a software change
   Answer: D. Flexibility of software is a key advantage. (Key point: Process change)

## Related in Instrumentation II

- [Case study: feasibility, drawbacks, convincing](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-2072kartik-feasibility) — Instrumentation II, chapter 10
- [Case study: existing vs proposed system](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-2074asoj) — Instrumentation II, chapter 10
- [Case study: recommended changes and convincing](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-recommend-changes) — Instrumentation II, chapter 10, asked 2×
- [Case study: revamping MBI system for CEO](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-ceo-revamp) — Instrumentation II, chapter 10
- [Case study: new system vs existing (cost, manpower)](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-cost-manpower-automation) — Instrumentation II, chapter 10, asked 4×
- [Case study: current control and recommendation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-existing-recommend-problems) — Instrumentation II, chapter 10, asked 3×

## Related in other subjects

- [LTI system and closed loop in modern systems](https://www.bctengineer.com/question.md?key=semester_3%2Fcontrol_systems%3Alti-define-cl-pronounced) — Control Systems, chapter 1
- [CASE, CASE environment and CASE tools](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Acase-environment) — Software Engineering, chapter 10
- [Classification and features of CASE tools](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Acase-classification) — Software Engineering, chapter 10
- [Instrumentation system with block diagram](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Ainstrumentation-system) — Basic Electronics Engineering, chapter 7, asked 3×