Glossary of Sensors, Switches & Automation Terms

Thanks to the Sensor, Switch, Smart Camera, and Machine Vision device OEM's who've helped us compile our listing here.

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Laser - An active electron device that converts input power into a narrow, intense beam of visible or infrared light. Term derived from “Light Amplification by Stimulated Emission Radiation.”

Laser diode - A silicon-based miniature electronic laser light source. latch (latching logic) A logic function in which an input signal locks “on” the output. The output remains “on” until a signal is applied as a second input to reset the latch.

Lateral approach - The approach of the target perpendicular to the reference axis. See Reference axis

LED (Light Emitting Diode) - A solid state “light” source that generates various colors of light.

Leakage current - The small amount of undesirable current inherent in solid state switches when they are in the “off” state. Becomes important if the resultant “off-stage” voltage across the load being switched is too high for the load to de-energize.

Lens - The optical component of a photoelectric sensor that focuses emitted light rays and/or focuses light rays upon the receiver.

Light emitting diode - See LED (Light Emitting Diode)

Light frequency - Frequency of modulated light.

Light operate mode (L.O. or L/O) - The program mode for a photoelectric sensor in which the output energizes (or delay logic begins) when the light intensity on the photodetector has sufficiently increased.

Limit switch - Electro-mechanical device that has an actuator, which when displaced causes a set of electrical contact(s) to change state (i.e. from "Off" to "On"). Various limit switch styles are shown in below illustration. SoftNoze has a unique Proxtrol™ PLS branded line of solid state limit switches, when combined with a user's inductive proximity sensor. Also see Switch Configuration to fully understand wiring options.

Linear output - The output of an analog sensor that has a straight-line relationship to a sensing parameter i.e., sensing distance.

Line voltage - Typical AC control power from 100V to 250V AC.

Load - A general term for a device or a circuit that draws power when switched by another device or circuit.

Load current - The maximum amount of current that a sensor will switch through its load.

Lock nut - An internally threaded, thin section, mounting fastener. Lock nuts may also be called a "jam nut", and they're commonly used to attach threaded barrel sensors to brackets and machine systems. A nut is placed on opposing sides of a bracket that a sensor is passed through, as the nuts are tightened and the bracket is placed into compression these nuts lock or jam up to the bracket- thus securing the sensor. Two other method used to secure both threaded and non-threaded sensors are Coupling nuts. Also, a single or a pair of Anti-vibration Nuts can be used.

Logic - The modification of an input signal that produces delayed, pulsed, latched, or other output response.

Logic level - Refers to the state of an input to or an output from a digital circuit (not applicable to analog circuits). It is always at one of only two possible voltages: “low” is a voltage usually less than 2 volts measured with respect to ground; and “high” is a voltage of some nominal level, usually within 2 volts of the positive supply.

Logic module - A sensing system accessory that interprets one or more input signals from sensors and modifies those input signals for control of a process.

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