Voices: Rezabek

How we can support a proliferation of smart devices

'For the efficacy of our engineering cleverness to endure, we need all our edge devices to migrate to a sustainable, standardized path,' argues John Rezabek in his latest column.

By John Rezabek
Jun 8, 2017

Can you solve the logic for a “test-reset-acknowledge” annunciator function in three relays or less? When refurbishing a previously-owned analyzer shelter with lower explosive limit (LEL) combustibles detectors and ambient oxygen sensors, the engineer decided he could replicate the local alarming and annunciation with a few conventional mechanical relays. For decades, the accepted functionality included a test circuit—a pushbutton to invoke the alarms and ensure the horn (audible alarm) sounded and all the lamps (visual indications) became illuminated, along with individual or common trouble alarms for the house. The other pushbuttons were acknowledge (to silence the horn) and reset (to return the annunciator to the normal state following a test or an actual alarm). It’s been canned-in, built-for-purpose annunciators since the mid-20th century.

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