What is the primary role of interposing relays in a PLC system?

The primary role of interposing relays in a PLC system is to perform automatic functions as dictated by the PLC. Interposing relays serve as an interface between the low-power PLC outputs and high-power devices or loads. When the PLC generates a control signal as part of its programmed operations, the interposing relay receives this signal and activates the corresponding high-power load safely and effectively.

Using interposing relays allows for the isolation of the PLC output circuits from the operational loads, providing both protection and flexibility within the system. This arrangement helps in managing the inductive loads that might otherwise cause back EMF, a form of electrical noise that can damage the PLC outputs. Therefore, interposing relays play a vital role in executing automatic control functions based on the PLC's programming.

The other options describe functions that are not the primary focus of interposing relays. Monitoring environmental conditions typically involves sensors, while facilitating communication with sensors is more related to inputs and data acquisition rather than the actuation performed by relays. Storing temporary data falls under the functions of specific memory components or data storage solutions in the PLC system, rather than the role of interposing relays.