---
title: "MBI block diagram and advantages in industry"
subject: "Instrumentation II"
chapter: 1
key: "semester_5/instrumentation_ii:mbi-block-advantages"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/mbi-block-advantages
site: BCT Engineering
---

# MBI block diagram and advantages in industry

Instrumentation II · Chapter 1: Microprocessor Based Instrumentation System

- Asked in: 2070 Asar, 4+4 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/mbi-block-advantages
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-1

## Question

Draw and explain the block diagram of microprocessor based instrumentation system. Also, list out advantages of implementing an MBI system in industrial plants for control and automation.

## Short answer

Block: sensor, conditioner, S/H, ADC, microprocessor with ROM/RAM, I/O for keypad/display, DAC/driver/actuator, communication. Advantages: automatic closed-loop control, multi-loop supervision, software flexibility, high accuracy, data logging, remote monitoring, reduced cost and downtime.

## Answer

#### Block diagram of an MBI system
```text
Sensor -> Signal conditioner -> S/H -> ADC --+
  ^                                          v
  |                                +------------------+
PLANT                              | Microprocessor   |<-> ROM/RAM
  |                                | (CPU, I/O ports) |<-> Keypad,
  v                                +------------------+    Display,
Actuator <- Driver <- DAC <----------------+  |           Printer,
                                              +-> Serial link
```

- **Sensor/transducer:** converts temperature, pressure, level or flow to an electrical signal.
- **Signal conditioning:** amplification, filtering, isolation and scaling.
- **S/H + ADC:** digitises each channel; a multiplexer shares the ADC among channels.
- **Microprocessor, ROM, RAM:** runs the monitoring and control program and stores data.
- **I/O ports:** keypad for set points, display, printer, alarm outputs.
- **DAC, driver, actuator:** operate valves, motors and heaters.
- **Communication interface:** reports to SCADA or a host PC.

#### Advantages in industrial plants for control and automation
1. Automatic closed-loop control (PID) keeps process variables at the set point, improving product quality.
2. A single unit supervises many loops, reducing instrument cost and panel space.
3. Fast detection of abnormal conditions with alarms and safe shutdown.
4. High accuracy and repeatability through digital processing and calibration.
5. Flexibility: a changed process needs only a program change.
6. Data logging, trend display and remote monitoring help maintenance and planning.
7. Reduced manpower, lower energy use and less wastage.
8. Self-diagnosis reduces downtime.

## Check yourself

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

1. How does automatic PID control help in industrial plants?
   A. Keeps process variables at the set point, improving product quality
   B. Makes variables fluctuate widely
   C. Removes the need for sensors
   D. Increases wastage
   Answer: A. Feedback control holds variables at set values. (Key point: Closed-loop control benefit)

2. Why is a multiplexer used before the ADC?
   A. To share one ADC among several channels
   B. To convert digital to analog
   C. To store the program
   D. To drive heaters
   Answer: A. It lets a single S/H and ADC serve many inputs. (Key point: Multiplexer purpose)

3. Why is a communication interface included?
   A. To increase sensor accuracy
   B. To report to SCADA or a host PC for remote monitoring
   C. To drive actuators
   D. To replace ROM
   Answer: B. It enables logging, trends and remote supervision. (Key point: Communication)

4. What is the benefit of self-diagnosis?
   A. Higher power use
   B. More manpower
   C. Reduced downtime
   D. Longer wiring
   Answer: C. Faults are detected quickly so maintenance is faster. (Key point: Self-diagnosis)

## Related in Instrumentation II

- [MBI block diagram, advantages and DMA](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-block-advantages-dma) — Instrumentation II, chapter 1
- [Types of microprocessor based instrumentation systems](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-types) — Instrumentation II, chapter 1
- [Features of microprocessor based instrumentation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-features) — Instrumentation II, chapter 1, asked 4×
- [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×
- [Rationale for microprocessor; open-loop MBI; DMA](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Arationale-open-loop-dma) — Instrumentation II, chapter 1
- [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

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- [Microprocessor based system and bus organization](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Amp-based-system-bus-organization) — Microprocessor, chapter 1, asked 5×
- [General block diagram of a control system](https://www.bctengineer.com/question.md?key=semester_3%2Fcontrol_systems%3Ageneral-bd-control-system) — Control Systems, chapter 1
- [Closed loop control system block diagram explained](https://www.bctengineer.com/question.md?key=semester_3%2Fcontrol_systems%3Awhat-is-cs-bd-closed-loop) — Control Systems, chapter 1, asked 4×