Name: What is Encoder?
Uploaded: 2019-04-13T06:49:25.000Z
Duration: 8 min 40 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Basic passive voice

An encoder is a device that is used in many industries to provide feedback.

Transition words & phrases

regardless of the type, which we will cover later,

senses position, direction, speed, or counts.

and the little bell to receive notifications of new RealPars videos.

Encoders will use motion, under a variety of technologies,

and translate it into an electrical signal.

That signal is then sent back to a controlling device,

such as a PLC, and is interpreted, meaning scaled,

to represent a value that will then be used within the program.

Some of the technologies involved in encoders are “magnetic”,

“mechanical”, “resistive”, and “optical”.

“Optical” is the most widely used encoder motion translating technology.

such as “absolute” and “incremental”.

We will describe those in greater detail in a future lesson.

But for now, an example of an incremental, optical type encoder

uses a beam of light that passes through a disk

that has opaque lines in a specific pattern,

On the other side of the disk is a photo sensing device

that will interpret the light, based on the pattern on the disk,

picture a shutter, blocking and unblocking the light.

The pulses of light are then converted to an electrical signal

which include “closed-loop” applications

such as “servo or VFD control”, “measuring”, and “counts”.

Here are some examples of processes that may use an encoder.

For VFD control, you may be running a pump,

on a VFD, to fill a tank full of a liquid.

and want to verify that the pumps VFD is at the requested speed.

An “encoder” on the VFD may be used for feedback of speed.

Next, let's give an example for a “measuring” process.

In this application, you will need to cut some aluminum product to a particular size.

You are passing a long roll, meaning hundreds of feet,

of the aluminum sheet through a cutting mechanism.

You need to determine the amount of aluminum fed,

so that you can cut the sheets to the proper size

that will be used in a separate manufacturing process.

and reading the material that is feeding through your cutting assembly,

will indicate the length of material that has been fed since the last cut.

That feedback can then be used to adjust the cutting blade

For an example of “counts”, consider this process.

You have a conveyor line that has bottles running on a conveyor.

They are counted by a photo-eye sensor when entering the assembly.

They have a cap with an aluminum tamper-proof foil on top

Once the foil is sealed, the bottle will then move down the conveyor line

and verified that it exited the cap sealing assembly

Some of the requirements for this station are:

The same number of bottles that enter the assembly

must exit in a “predetermined time frame”.

The bottle must not remain in front of an “entrance” or “exit” sensor.

The bottle must not be exposed to the inductive sealer

longer than a predetermined amount of time.

You must make this assembly flexible enough

Consider a prescription bottle, easy right? No handles,

with a somewhat small cap and a very large handle.

How in the world are you going to meet the requirements for the machine

and remain flexible? If you put a pill bottle in, yep, easy peasy right?

bottle in, seal, bottle out, no sensors blocked.

bottle in, seal, tips over and isn't counted out,

machine halts and alerts an operator of a malfunction.

Bottle in, cap passes in front of an entrance sensor,

the system faults because it sees a blockage at the entrance.

How do you tell the machine that this is expected behavior?

“An encoder” of course, and a “selector switch” for a setup mode.

To set up, insert your product, in this case, the antifreeze bottle.

Your program reads an entrance on the sensor

as well as determines that this is a “cap” and records that fact.

and determines that this is not “cap”

and must be some other acceptable part of the bottle, possibly a handle.

The single bottle continues down the line

At that point,you again record the encoder value.

that registered at the entrance and exit.

In the code, you subtract the entrance from the exit

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What is Encoder?

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