Digital Readouts Information

Digital readoutDigital readouts are specialized displays for position and dimension readings from inspection gages and linear scales, or rotary encoders on machine tools. 


Digital readouts have several common display characteristics. These include:

  • input axes
  • input channels
  • resolution
  • number of digits
  • number of lines

The number of axes specifies the number of input axes the digital readout can measure on. It is common for digital readouts to measure on anywhere from one to four axes of measurement but capacities for greater than four exist. Input channels are the number of all analog input channels. This includes both general and specific types. Resolution is the smallest measurement the readout can display. The number of digits and lines the readout can display are also important considerations.


Digital readouts can accept inputs from any number of sources for different applications. These include:

  • coordinate measuring machines
  • dimensional gages
  • machine tools
  • measuring microscopes
  • optical comparators

Coordinate measuring machines (CMMs) are mechanical systems designed to move a measuring probe to determine coordinates of points on a workpiece surface. Dimensional gages provide quantitative measurement of dimensional and form attributes such as wall thickness, depth, height, length, I.D., O.D., taper, or bore. A machine tool is a piece of equipment used for machining components. A measuring microscope is a microscope used by toolmakers for measuring properties of tools. These microscopes are often used for dimensional measurement with lower magnifying powers that allow for brighter, sharper images combined with a wide field of view. An optical comparator is an instrument that projects a magnified image or profile of a part onto a screen for comparison to a standard overlay profile or scale. They are used to measure, gage, test, inspect, or examine parts for compliance with specifications. Common inputs accepted by digital readouts include analog voltage, analog current, encoder, fiber optic, LVDT, parallel, resistance, serial, temperature, and TTL.


Display features commonly found on digital readouts include alphanumeric displays, graphic displays, and numeric displays. The display technology can be CRT (cathode ray tube), LCD (liquid crystal display), and LED (light emitting diode). The display units can be English, metric, or both. General features common to digital readouts include absolute and incremental modes, adjustable displays, alarms, integral keypads, memory and data storage, programmability, set point options, and zero reset.

Related Information

Electronics360—The Wheatstone Bridge: Still the Preferred Sensor-Interface Topology After 180 Years

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Image credit: 

Glenn McKechnie / CC BY-SA 3.0


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