Which of the following is NOT a key purpose of industrial Ethernet networks?

Industrial Ethernet networks primarily focus on facilitating communication and data transfer between devices. Their key purposes include data transmission, which encompasses the transferring of real-time information between machines and control systems in a manufacturing environment. Device control is another central aspect, as these networks enable the management and operation of connected devices, ensuring they function as intended in an automated setting.

Environmental monitoring plays a role in industrial settings, often leveraging Ethernet networks to collect and analyze data related to environmental conditions, such as temperature and humidity, which can affect manufacturing processes.

Power regulation, however, is not a primary function of industrial Ethernet networks. While power management may be a concern in industry and certain protocols might include aspects of power monitoring, the core role of industrial Ethernet is not to directly regulate power. Instead, it focuses on enabling effective communication and control among devices in a networked environment. Hence, this option is identified as not being a key purpose of industrial Ethernet networks.