---
title: "Character transmission time at 1200 baud"
subject: "Instrumentation II"
chapter: 3
key: "semester_5/instrumentation_ii:baud-time-1200"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/baud-time-1200
site: BCT Engineering
---

# Character transmission time at 1200 baud

Instrumentation II · Chapter 3: Serial Interfacing With Microprocessor Based System

- Asked in: 2074 Asoj, 2 marks; 2068 Baisakh (old course), 4 marks (asked 2 times)
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/baud-time-1200
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-3

## Question

What is the time required for transmission of a character with one start bit, seven data bits, one parity bit, and one stop bit with 1200 baud?

## Short answer

At 1200 baud, one bit time is 0.83 ms. A character with1 start,7 data,1 parity, and1 stop bit (10 bits) takes8.333 ms to transmit.

## Answer

Baud rate = number of signal elements (bits here) per second, so at 1200 baud the bit rate is 1200 bits/s (one signal element per bit).

#### Frame
Start bit + data bits + parity bit + stop bit = 1 + 7 + 1 + 1 = **10 bits per character**.

#### Calculation
```text
 Bit time      = 1 / 1200 = 0.8333 ms
 Character time = 10 bits x 0.8333 ms = 8.333 ms
 Characters per second = 1200 / 10 = 120 characters/s
```
**Answer: 8.33 ms per character** (about 120 characters per second). Only 7 of the 10 bits are information, so the effective data rate is 7 x 120 = 840 bits/s.

## Check yourself

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

1. How many bits are in one character with 1 start, 7 data, 1 parity, 1 stop?
   A. 9
   B. 10
   C. 8
   D. 11
   Answer: B. 1 + 7 + 1 + 1 = 10 bits. (Key point: Frame bits)

2. What is the bit time at 1200 baud (one bit per element)?
   A. 0.833 ms
   B. 8.33 ms
   C. 1.2 ms
   D. 0.12 ms
   Answer: A. 1/1200 = 0.8333 ms. (Key point: Bit time)

3. What is the time per character?
   A. 0.833 ms
   B. 1.2 ms
   C. 8.33 ms
   D. 83.3 ms
   Answer: C. 10 bits x 0.8333 ms = 8.33 ms. (Key point: Character time)

4. What is the effective data rate in bits/s (data bits only)?
   A. 1200
   B. 840
   C. 960
   D. 720
   Answer: B. 120 characters/s x 7 data bits = 840 bits/s. (Key point: Effective rate)

## Related in Instrumentation II

- [Bit rate, baud rate and character time at 9600](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Abaud-time-engineer) — Instrumentation II, chapter 3
- [RS-232C importance; time to transmit a string at 4800 baud](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ars232c-string-time-4800) — Instrumentation II, chapter 3
- [Asynchronous serial transfer of a character](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aasync-7bit-ascii-2stop) — Instrumentation II, chapter 3

## Related in other subjects

- [Parity bits and 3-bit even parity generator](https://www.bctengineer.com/question.md?key=semester_3%2Fdigital_logic%3Aparity-even-generator-3bit) — Digital Logic, chapter 4, asked 2×
- [Parity bits and 3-bit odd parity generator](https://www.bctengineer.com/question.md?key=semester_3%2Fdigital_logic%3Aparity-odd-generator-3bit) — Digital Logic, chapter 4, asked 2×