Which of the following describes how Modbus operates?

Modbus operates primarily as a master-slave protocol, where a single master device can communicate with one or more slave devices. In this configuration, the master initiates all communication, sending requests to the slave devices and waiting for their responses. This structure ensures clear control over the data flow and prevents collisions in communication, which is particularly valuable in industrial settings where reliable data exchange is critical.

In the master-slave architecture, the master can package commands and queries, while the slaves respond only when specifically requested. This setup not only simplifies the communication process but also enhances the efficiency of data retrieval from multiple devices, as the master can poll slaves in a defined sequence.

The other options present alternatives that do not accurately characterize Modbus operation. Peer-to-peer communication typically involves multiple devices exchanging data directly without a central authority, which is not how Modbus functions. Broadcasting messages and multicast addressing suggest methods where messages are sent to multiple devices simultaneously; however, Modbus relies on the master-slave structure for systematic communication.

Understanding the master-slave concept is crucial in industrial cyber security contexts because it highlights how devices interact and the potential vulnerabilities associated with such communication patterns, emphasizing the importance of securing the master device to maintain the integrity and reliability of the entire network.