What is a key characteristic of smoke detectors with control output functions?

A key characteristic of smoke detectors with control output functions is their ability to perform controlling actions, such as initiating a elevator recall during a fire alarm event. This means that when smoke is detected, these devices can not only alert occupants through alarms but can also send signals to other systems within a building, effectively managing and altering the environment for safety and emergency response. This functionality is essential in complex safety systems where coordinated actions are necessary to ensure the safety of individuals and the efficient operation of emergency protocols.

In contrast, the other options do not accurately represent the capabilities of these smoke detectors or their intended applications. For example, stating they are only for residential use does not reflect their versatility in various settings, including commercial and industrial applications. Additionally, asserting that they provide no output to control units mischaracterizes their primary function, while stating they trigger an alarm without any conditions overlooks the fact that control output smoke detectors work based on specific triggering parameters and concerns for safety management systems.