NSE 7 – OT Security 7.2 — Question 38

Which communication method is used by the Modbus protocol?

Answer options

• A. It uses OSI Layer 2 and both the primary/secondary devices send data based on a matching token ring.
• B. It uses OSI Layer 2 and the secondary device sends data based on request from primary device.
• C. It uses OSI Layer 2 and both the primary/secondary devices always send data during the communication.
• D. It uses OSI Layer 2 and the primary device sends data based on request from secondary device.

Correct answer: B

Explanation

The correct answer is B because Modbus operates on a master-slave architecture where the primary device requests data from the secondary device. Options A, C, and D are incorrect as they misrepresent the communication flow and the roles of the primary and secondary devices in the Modbus protocol.