Example take a seller, before inventing barcodes, he uses a price list for knowing the details of item. But it is very consuming for both searching and preparing the price list. Later this retail outlet is computerized .In these details of items were already kept in database. Using the code number of the item the seller access the details of the item. But here also some problems arise. We must remember the code number of each item and whenever the price changes, we must update the entire database. If new product comes into existence, then we have to give new code to that product. It is risky process.
?????????? If we use barcodes, there is no such problem. We get online information without giving any data to the computer. If the manufacturing company produces large quantity of products, then these barcodes are very useful.
The idea was come in 1932.But it implement take many years. The actual usage of barcodes was started in 1970.From last 15 years usage of barcodes increases rapidly.
First barcode product is Wrengly?s checking sum and it is scanned at marsh?s super market around 25 years ago. Then the little barcode has increased and multitude and today one can see barcodes printed on every item in retail?s stores throughout the world.?
?????????????? Now we are observing these barcodes in every item that we come across. This is useful for both manufacturer and seller.
What is barcode? It consists of parallel and adjacent bars. It also consists of some narrow bars and some wide bars. The width and height of bars are specified according to the numbers or characters given to it. But the actual data kept on the bars. These numbers are only for references.
????????? Structure of barcodes? The basic structure of barcodes consists of a start and stop characters. And one or more data characters and a check sum character.
????????? Start and stop characters are useful for barcode readers for knowing where the barcode is started and where it is ended. The data character consists of batch number, price of the item, country name, item code etc. The check sum character is used for knowing whether the barcode reader scan the barcode correctly or not.
TYPES OF BARCODES:
????????? We are using three types of barcodes. They are-
??????????????????? 1.Numeric-only barcodes.
??????????????????? 2.Alpha- numeric barcodes.
??????????????????? 3.Two-dimentional barcodes.
1.Numeric-only barcodes:
This type of barcodes represents only numbers. These numeric only barcodes are mostly used in retail market and manufacturing industry. Symbolagies used in numeric-only barcodes are-
EAN-13:
These barcode standard is used by all over the world except America and Canada. This is mainly used in retail sales. It consists of 13 numbers. First 2 or 3 number represents country name where the product is manufactured and next 4 or 5 numbers represents code. Next 5 numbers represents product and last number represents check sum.
Check sum is used to know whether the barcode is scanned correctly or not. It is prepared using before 12 numbers. The check sum is prepared based on modulo10 calculation. First it takes the even number sum and multiplied it with 3.Then add odd number sum and? subtract this value from the nearest 10 multiple. Then the value is equal to last digit of the barcode.
When the product is scanned, then it calculates the check sum. If it matches then we can identify that the barcode is scanned correctly.
EAN-8:
This is similar to Ean-13. The only difference is, EAN-13 uses 13 numbers where as EAN-8 uses 8 numbers. If only less space available for a product or to represent less data then this symbol is used. It is a compressed version.
UPC-A:
America and Canada use this barcodes. The products manufactured sold by America and Canada use this barcode. When any other countries want to sell their products to America and Canada these type of barcodes are must.??????????????????????????????????????????????????????????
It consists of 12 numbers. First number represents for which the product is used and the next 5 numbers represents the manufactured ID and next 5 numbers represents the code of that product and the last number represents check sum.
The check sum calculation is similar to calculation in EAN. But the method used for even and odd numbers is different. In EAN, we multiply even number sum with 3 but here, we multiply the odd number sum with Remaining is same as EAN.?
2.Alpha- numeric barcodes:
In this barcodes, both numbers and characters. The sybologies used in this type of barcodes are-
CODE 39:
It is used in all factories and government organization in all over the world. This symbol is also called as UDP-3 or 3of9.This recognized by ANSI. The bars in code represents 0 to 9 digits, A-Z characters and special characters. Each barcode consists of start and stop character. Each character consists of 15 barcode elements. It doesn?t consist of check sum.
CODE 93:
It is similar to CODE 39.But only difference is , in CODE 39 , each character represents 15 elements where as in? CODE 93 ,each character represents 13 elements. So, this is small version of CODE 39.
CODE 128:
This barcode is used in all the fields. Here we can use both upper and lower case letters and digits from 0 to 9 and symbols and codes. These codes are divided into 3 subsets namely A, B, C.This is because to use more? number of codes. Each subset is starts with separate code. It has the facility to change from one subset to another at the middle of the code. By adding a control character, we can change from one subset to another. They are-
Subset-A:? ASCII symbols, capitals, control characters.
Subset-B: ASCII symbols, small letter.
Subset-C: Here compressed characters are used. i.e. two??????
Characters are compressed to form a character.
It consists of check sum. But based on the subset the check sum is calculated. It is also called Modulo 103. The calculation of check sum is difficult.
3.Two-dimentional barcodes:
Generally, we use one-dimensional barcodes. But in this we can use only 20 to 25 characters. To represents more characters we use 2D barcodes.
PDF-417:
It is rectangle in shape. Using this we can store 1800 ASCII characters or 1100 binary characters. This symbol size can be changed using the data it stores. If it consists of large amount of data, then we can divide it into two PDF-417 barcodes and link them together. So, we can store any amount of data using links.
It is mainly used when we want to send large amount of data over tables and to represent to the technical specifications and collaborations on electrical products. It is also used to store the fingerer prints for driving license.?
Data matrix:
It can store one to two thousand characters. It is square in shape having 0.001 to 14 inches side. This type of barcodes also printed 24-pin dot matrix. It is used to print the product information on electric plates, serial numbers to identify medical instruments in Japan, lenses and circuit boards.?
Maxi code:
This barcodes stores 93 characters. If we want to store large amount of data in small area then it is used. This is similar to Bulls Eye. It was developed by UPS (United Parcel Service). To start packages over fast conveyer lens, it is used.
BARCODE WORKING:
Barcode works on the basis of character recognization for identify. These characters barcode reader is used for knowing the details of the product.
Barcode reader consists of Scanner, decoder and cable (it acts as interface between reader and pc. The scanned data transferred to pc). When this is passed over the barcode the light source of scanner observes the dark bark but it is not reflected. It is reflected by light spaces. A photocell detector in the scanner receives the reflected light spaces and converts the light into electronic signal. The decoder converts this signals into characters. These characters passed to computer throw an interface.
Barcode reader is used for knowing the details, which are kept in the bars.?
BARCODE READERS:
These are three basic structures for barcode reader. They are-
????????? 1. fixed reader.
????????? 2. portable batch readers.
????????? 3. portable radio frequency readers.
Fixed reader:
These are attached to their host computers and terminals. And transmit the one data item at a time as the data is scanned. Wand scanners, CCD scanners, laser scanners come to this category.
Portable batch readers:
These readers bitterly operated and store the data into memory. Later the batch of information is transferred into host computer.
Portable radio frequency reader:???
These readers are battery operated and transmit data real-time, on-line more importery, the real-time, two-way communication allows the host to operator.?
The basic reader consists of a decoder and scanner and also used a cable that acts as an interface between decoder and the computer. The basic operation of scanner is to scan the barcode symbol and provide an electric output that corresponding to the bars and spaces of that barcode.
A decoder is usually a separate box that takes the digitalized bars and space patterns and decodes them to the correct data, and transmits the data to the computer over wires or wireless immediately on a batch basis.
Portable Batch Readers:
It includes a display, keypad barcode decoding capabilities, RS-232 communication port, batteries and memory for and program storage for barcode collection. The system can be equipped with barcode wand, CCD or laser scanners.
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