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What is Encoder? - YouTube
Channel: RealPars
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an encoder is a device that is used in
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many industries to provide feedback in
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the most basic terms an encoder
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regardless of the type which we will
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cover later senses position direction
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speed or counts
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one
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encoders will use motion under a variety
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of technologies and translate it into an
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electrical signal that signal is then
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sent back to a controlling device such
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as a PLC and is interpreted meaning
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scaled to represent a value that will
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then be used within the program
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analogies involved in encoders are
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magnetic mechanical resistive and
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optical optical is the most widely used
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encoder motion translating technology
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are different types of encoders such as
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absolute and incremental we will
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describe those in greater detail in a
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future lesson
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but for now an example of an incremental
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optical type encoder uses a beam of
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light that passes through a disk that
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has opaque lines in a specific pattern
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somewhat like the spokes of a wheel
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on the other side of the disk is a photo
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sensing device that will interpret the
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light based on the pattern on the disk
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picture a shutter blocking and
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unblocking the light
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the pulses of light are then converted
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to an electrical signal to be sent back
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to the processor through the encoders
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output
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encoders have a wide range of uses which
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include closed loop applications such as
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servo or VFD control measuring and
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counts here are some examples of
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processes that may use an encoder
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VFD control you may be running a pump on
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a VFD to fill a tank full of a liquid
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you are requesting a certain speed and
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want to verify that the pumps VFD is at
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the requested speed an encoder on the
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VFD may be used for feedback of speed
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next let's give an example for a
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measuring process in this application
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you will need to cut some aluminum
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product to a particular size you are
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passing a long roll meaning hundreds of
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feet of the aluminum sheet through a
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cutting mechanism you need to determine
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the amount of aluminum fed so that you
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can cut the sheets to the proper size
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that will be used in a separate
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manufacturing process
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an encoder attached to the conveyor and
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reading the material that is feeding
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through your cutting assembly will
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indicate the length of material that has
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been fed since the last cut that
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feedback can then be used to adjust the
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cutting blade to sever the length
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required
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for an example of counts consider this
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process you have a conveyor line that
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has bottles running on a conveyor they
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are counted by a photo I sensor when
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entering the assembly they have a cap
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with an aluminum tamper proof foil on
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top that needs to adhere to the bottle
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once the foil is sealed the bottle will
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then move down the conveyor line and
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verified that it exited the cap ceiling
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assembly via and exit photo I sensor
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some of the requirements for this
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station are the same number of bottles
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that enter the assembly must exit in a
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predetermined timeframe the bottle must
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not remain in front of an entrance or
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exit sensor
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the bottle must not be exposed to the
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inductive sealer longer than a
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predetermined amount of time
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you must make this assembly flexible
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enough to handle many types of bottles
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and entrance and exit sensor placement
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consider a prescription bottle easy
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right no handles just a bottle that is a
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standard size now consider an antifreeze
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bottle with a somewhat small cap and a
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very large handle
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how in the world are you going to meet
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the requirements for the machine and
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remain flexible if you put a pill bottle
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in yep
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easy peasy right bottle in seal bottle
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out no censors blocked
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if any of the requirements fail bottle
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in seal tips over and isn't counted out
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Machine halts and alerts on operator of
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a malfunction
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how about the antifreeze bottle
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bottle in cap passes in front of an
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entrance sensor bottle counted then the
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handle the system faults because it sees
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a blockage at the entrance
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how do you tell the machine that this is
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expected behavior an encoder of course
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and a selector switch for a set up mode
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setup insert your product in this case
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the antifreeze bottle you make sure to
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feed cap first and it must contain a
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foil your program reads an entrance on
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the sensor and records an encoder
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reading as well as determines that this
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is a cap and records that fact your
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program then reads another entrance and
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determines that this is not cap it must
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be some other acceptable part of the
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bottle possibly a handle the single
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bottle continues down the line
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where the exit sensor is triggered at
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that point you again record the encoder
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value you now have an encoder count that
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registered at the entrance and exit
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in the code you subtract the entrance
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from the exit and you have a bottle
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count you now know precisely how long it
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will take that bottle to move through
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the system meeting thee must enter an
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exit in a predetermined timeframe in
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this case encoder counts
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you have also made the flexibility
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aspect of different types of bottles as
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well as being able to place the entrance
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and exit sensors any reasonable distance
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apart when back in run mode the code
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knows that there's a handle to ignore
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when it comes into the process and
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doesn't fault a machine you register the
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encoder at each bottle entrance and
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predetermine when the bottle must exit
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if the bottle doesn't exit the machine
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in a timely manner which is based on
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your projection and the current encoder
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count the Machine faults this is a great
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use of an encoder that is fully
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configurable count in count out subtract
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done
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don't miss the next lesson where we are
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going to discuss incremental and
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absolute encoders
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want to learn
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see programming in an easy-to-understand
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format and take your career to the next
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level head on over to real parse com
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