Feb 18, 2011

Different Types Of Encoder Used In Automation Industry

In a wide range of Applications in Industrial Automation , One device which is all time favorite for feedback purpose is "Encoder". As it has got capability to be used in Rugged and Noisy Environment , Low cost so still its best choice for feedback purpose and dominates the market.Here in this post we will see about the different output types and Encoder Operating Principle.

||Different Types Of Encoder In Automation Industry||
There are two types of Encoders broadly either in rotary or linear configurations. Every Encoder comes with a predefined PPR and the Maximum Frequency. Let us see how a rotary optical encoder gives the quadrature format. A rotary optical encoder has two output wires as A and B for giving out the quadrature format output. This encoder also Provides the Index pulse for every single rotation completed.

Construction of Rotary Optical Encoder:-
The most common configuration for this type of encoder consists of series of Opaque Parts. The Encoder unit consists of Light Emitting Diode(LED) or Pair of sensor for Giving out the signal for A and B.Now the Opaque Array Segments are arranged in such a way that when it is rotated the A and B signal will be 90 degree to each other. The Index pulse provided after every single rotation of Encoder Shaft can be used for Homing Purpose. See the Below Picture for the overview of Construction part and A , B and I pulses.

Image Source:- automation.com

One of advantage of Index Pulse is used for "auto-correct" feature. The Index pulse will be fixed for the same position of Motor's shaft for every rotation and if there is noise and somehow the number of counts increase or decrease then we can get to know and auto-correct the same.

But with the Incremental Encoders there is a problem ,when we start our system we can't get to now the actual position , so we home the machine . But here comes the another solution and answer is "Absolute Encoders" , with these encoders it is possible to know the actual location every time. These comes in a wide range of Outputs , up to 25 bits.
What is the Difference Between Incremental & Absolute Encoder.

But in earlier time when there were No LED or sensor for Generating the 90 deg offset pulses , non-optical position encoder were used. These are known as "Resolver".The Output of Resolver is in Sinusoidal waveform.

Another Type of Encoder is Magnetic Encoder. The best advantage of this type of Encoder is that the sensor and the encoding disk are not in contact , so it can be rigid packed and a very good solution for noisy and dirty operating conditions.

You can subscribe to get all latest Updates about Encoders, PLC programming and SCADA Script.
Subscribe to Automation-Talk by Email

Advertisements :-


Post a Comment

Receive all updates via Facebook. Just Click the Like Button Below