Which device enables wireless communication in CPS nodes?

The device that enables wireless communication in Cyber-Physical System (CPS) nodes is the radio modem. This component serves a crucial function by facilitating data transmission over wireless channels, which is essential for maintaining communication among various nodes in a distributed system.

Radio modems are specifically designed to encode and decode signals for transmission, converting data from the CPS nodes into a format suitable for wireless transfer. Their role is to ensure that the information gathered by sensors or processed by controllers can be communicated effectively without physical wiring constraints. This enhances the flexibility and adaptability of CPS architectures, particularly in environments where mobility or accessibility is a concern.

In contrast, sensors are primarily used to collect data about the environment, controllers are responsible for processing this data and making decisions, and actuators are tasked with executing physical actions based on the controllers' outputs. While all these components are integral to the functioning of CPS, only the radio modem specifically addresses the need for wireless communication, making it the correct choice in this context.