What it is and where it lands
The Omron E2S-Q21 5M is an inductive proximity switch from the E2S series, used for non-contact detection of metal targets in automated machinery, conveyors, and packaging lines. It switches when a ferrous or non-ferrous metal enters its sensing field, providing a digital output to a PLC or relay—routinely specified for position sensing, part-present verification, and end-of-travel limits in industrial equipment.