Frequently Asked Questions

• I currently use rotary encoders. Can I use linear encoders?
• What is Inductive Sensing?
• Is it simple to install the LN Linear Encoder?
• What measuring lengths are available?
• What resolutions are available?
• What is the periodic index?
• Do you sell compatible displays?

The suitability of a linear encoder for a particular application is dependent on many factors, some mechanical and some electrical. From a mechanical perspective, the type of measurement required and the mechanical feasibility of integrating a rotary or a linear encoder will often dictate one over the other. From an electrical integration standpoint, LN linear encoder provides industry standard differential quadrature outputs and is therefore compatible with the same displays, controllers, PLC's and counters that an incremental rotary encoder would be. The LN linear encoder offers integrators the flexibility to use the same interface devices as with their rotary encoders, eliminating the need to retool an entire control system. 

Inductive sensing measures the interaction of an electromagnetic field with surrounding metallic materials. The mechanics of inductive sensing begin with a standard reference signal being transmitted through a drive coil. Adjacent sensing coils monitor the resultant electromagnetic force (EMF) field. This EMF field is distorted in a predictable and repeatable way by its proximity to certain metals. Therefore, if a scale with cyclic physical properties is introduced into the magnetic field, the position of the sensing head along the scale can be precisely determined by observing the electromagnetic field’s reaction. 

The LN linear encoder combines inductive sensing technology with a stainless steel scale, internal nickel-chrome ball bearings and a sealed IP67 rated read head.  The read head performs the sensing of the cyclic distortion in the EMF.  An onboard digital signal processor (DSP) analyzes these distortions and calculates the absolute position of the read head. The DSP then translates this positional information into a series of digital square waves representative of the amount of movement that has occurred. These square wave signals can then be used by PLCs, data acquisition (DAQ) systems or readout devices to precisely control or monitor position. 

The installation procedure for the LN linear encoder is very forgiving. Each encoder is delivered with the appropriate universal mounting kit necessary to properly mount it's scale. The universal mounts are easily adjustable, making the task of aligning the scale with the axis of travel quick and easy. The mounting kit also includes shims to be used in aligning the read head parallel with the axis of travel. A detailed installation guide accompanies each encoder.

To view a basic linear encoder installation example, download Installing BEI LN linear encoders *( PowerPoint, 1.1MB)
*Note: Installation example meant for demonstration purposes only and may not reflect your exact installation requirements.

Measuring lengths in even numbers of inches (2, 4, 6, etc) are readily available, up to a maximum of 433 inches (36 feet).

LN encoders are available in resolutions of 10, 5, 2, 1 and 0.5 micrometers.

A periodic index is similar to the Z index on our rotary encoders. On the LN series linear encoder, a Z index signal is generated every ½ inch, coincident with the center of each spherical element inside the scale tube.

We offer the SA100 digital display for use with the LN linear encoder. The SA100 accepts a 5VDC differential quadrature input and displays linear distance in inches or millimeters. Front panel controls allow the user to change axis and display resolutions, sense of direction, scale factors and even enter linear error compensation factors. Linear Encoder Digital Display