Instrumentation Questions

PROFIBUS Quiz: Top 25 Advanced Interview MCQs with Answers for Automation Professionals

February 11, 2025

Welcome to the ultimate PROFIBUS communication quiz! This quiz is intended for professionals in the process industries who want to test their knowledge of PROFIBUS communications. Dive into 25 carefully crafted advanced multiple-choice questions that cover important topics of network architecture, troubleshooting, diagnosis, and implementation. To help you learn more, each question is answered in detail with explanations. Whether you’re preparing for an interview, certification, or simply want to test your knowledge, this quiz provides a thorough review of the important ideas and scenarios you may meet in real-world applications. Improve your abilities and gain insight into the complexities of PROFIBUS in the process industries!

Challenge your PROFIBUS knowledge with 25 advanced MCQs, answers, and explanations designed for automation professionals.

Challenge your knowledge with this Advanced PROFIBUS Communication Quiz! It is intended for process industry specialists and includes 25 hard multiple-choice questions about troubleshooting, architecture, and implementation. Each question has extensive answers and explanations, making it excellent for interview practice or skill development. Are you ready to learn PROFIBUS communication? Dive in and discover the key elements of this vital industrial protocol!

1 / 25

Which layer in PROFIBUS is responsible for device-specific profiles like PROFIdrive?

Data Link layer

Physical layer

Application layer

Network layer

Device-specific profiles like PROFIdrive operate at the Application layer, defining standardized communication interfaces for specific device types like drives and controllers.

2 / 25

How does PROFIBUS achieve deterministic communication?

By assigning time slots for each slave

Using cyclic polling by the master

Through priority-based message handling

By dynamically adjusting the baud rate

PROFIBUS ensures deterministic communication through cyclic polling, where the master continuously queries each slave in a predefined sequence, ensuring timely data exchange.

3 / 25

How are redundant masters implemented in a PROFIBUS network?

By configuring slave devices to recognize multiple masters

Using token passing between the masters

Employing a hot-standby mechanism

Configuring a master-slave loop

Redundant masters are implemented using a hot-standby mechanism, where one master takes over if the primary fails.

4 / 25

What type of topology does PROFIBUS DP typically use?

Ring

Star

Linear (Bus)

Mesh

PROFIBUS DP primarily uses a linear topology for device interconnection, with terminations at both ends.

5 / 25

What is the function of the PROFIBUS FMS protocol?

Real-time control of field devices

High-level messaging between automation systems

Handling cyclic data exchange

Error detection and correction

The Fieldbus Message Specification (FMS) protocol is used for complex, high-level communication between automation systems.

6 / 25

What is the typical baud rate used in PROFIBUS PA communication?

9600 bps

31.25 kbps

1 Mbps

12 Mbps

PROFIBUS PA operates at a fixed baud rate of 31.25 kbps, ensuring compatibility with intrinsically safe environments.

7 / 25

How is bus termination achieved in a PROFIBUS DP network?

By connecting a 24V power supply

Using a built-in termination resistor at both ends

Installing a signal booster

Enabling an automatic termination option

Proper bus termination using resistors ensures signal integrity and prevents reflections in the network.

8 / 25

Which diagnostic feature helps identify failing devices in a PROFIBUS network?

Live list

Master redundancy

Network topology mapper

Oscilloscope readings

The live list maintained by the master identifies all active devices, helping detect any missing or failing devices.

9 / 25

What does the watchdog timer in a PROFIBUS slave do?

Ensures the master is always active

Tracks the slave’s response time

Monitors data consistency on the bus

Resets the slave if communication is lost

The watchdog timer resets the slave if there’s no communication from the master within a defined period, ensuring system reliability.

10 / 25

What is the typical voltage level used for RS-485 communication in PROFIBUS?

12V

-7V to +12V

-3V to +5V

RS-485 signaling uses differential voltage levels typically ranging between -7V and +12V for robust communication.

11 / 25

How does PROFIBUS handle communication errors?

Retransmits the corrupted frame automatically

Ignores the faulty data

Stops communication until the error is resolved

Disconnects the faulty device from the network

PROFIBUS detects errors using checksums and retransmits corrupted frames to maintain reliable communication.

12 / 25

What is the main function of a PROFIBUS repeater?

Enhance network security

Extend the cable length and strengthen signals

Assign unique addresses to devices

Convert PROFIBUS DP to PA

Repeaters regenerate and amplify signals, allowing longer cable lengths and ensuring data integrity over extended distances.

13 / 25

Which of the following is a key advantage of using PROFIBUS PA?

Faster data transfer rates

Capability to operate in hazardous environments

Compatibility with Modbus devices

Built-in Ethernet communication

PROFIBUS PA supports intrinsic safety, making it ideal for hazardous areas in process industries

14 / 25

What is the maximum data transmission speed of PROFIBUS DP?

500 kbps

1 Mbps

12 Mbps

24 Mbps

PROFIBUS DP supports a maximum data transmission speed of 12 Mbps, ensuring high-speed communication in industrial automation.

15 / 25

What happens if two PROFIBUS devices have the same address?

The network switches to safe mode.

Communication conflicts occur, causing network failure.

The master resolves the conflict automatically.

The devices merge their data streams.

Each device must have a unique address; duplicate addresses lead to communication errors and potential network breakdowns.

16 / 25

What is the purpose of the cyclic communication in PROFIBUS?

Real-time exchange of process data

Storing configuration files

Updating firmware remotely

Conducting diagnostics

Cyclic communication is used for fast, real-time data exchange, ensuring process parameters are continuously updated between the master and slaves.

17 / 25

Which layer of the OSI model is implemented in the PROFIBUS protocol?

Physical and Data Link layers

Application layer only

Network and Transport layers

Session and Presentation layers

PROFIBUS operates primarily at the Physical and Data Link layers, enabling efficient communication between devices.

18 / 25

What diagnostic tool is most commonly used to detect cable faults in PROFIBUS?

Protocol analyzer

Time Domain Reflectometer (TDR)

Oscilloscope

Multimeter

TDR is widely used to detect cable faults like breaks, shorts, and impedance mismatches in PROFIBUS networks.

19 / 25

In PROFIBUS, what does the token passing mechanism achieve?

Reduces latency in message delivery

Enables synchronization between masters

Controls access to the bus for masters

Enhances fault tolerance

The token passing mechanism ensures only one master accesses the network bus at a time, preventing communication conflicts.

20 / 25

What is the role of the FDL (Fieldbus Data Link) layer in PROFIBUS?

Manages cyclic and acyclic communication

Handles physical wiring of devices

Translates application commands into signals

Ensures device authentication

The FDL layer is responsible for data exchange between PROFIBUS devices, handling cyclic data for real-time operations and acyclic data for configuration and diagnostics.

21 / 25

What is the maximum allowable length of a PROFIBUS DP cable at 12 Mbps?

100 meters

200 meters

1200 meters

400 meters

At the highest baud rate of 12 Mbps, the maximum cable length for PROFIBUS DP is limited to 100 meters without repeaters.

22 / 25

How does PROFIBUS PA differ from PROFIBUS DP?

PA operates on lower voltage and supports intrinsic safety.

PA supports faster communication speeds than DP.

PA is used for diagnostic purposes only.

PA doesn’t require a GSD file.

PROFIBUS PA is designed for process automation, operating on 31.25 kbps with intrinsic safety, making it suitable for hazardous areas.

23 / 25

Which medium is commonly used in PROFIBUS DP communication?

Fiber optic cable

Twisted-pair cable (RS-485)

Coaxial cable

Wireless

PROFIBUS DP primarily uses RS-485 communication over twisted-pair cables for high-speed, noise-immune data transmission.

24 / 25

What is the main purpose of the GSD file in a PROFIBUS network?

To store the network topology

To define device-specific parameters

To monitor data communication

To enable real-time diagnostics

The GSD file (General Station Description) contains details about device configuration, baud rates, and supported data formats, enabling proper integration into the network.

25 / 25

What is the maximum number of devices that can be connected to a PROFIBUS DP network?

126

128

PROFIBUS DP allows a maximum of 126 nodes (including the master) on a single network. This includes both master and slave devices.

Your score is

The average score is 65%

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Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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