Code 128 Introduction, Data, Check Digit, Structure, Application

Barcode Introduction > Code 128

Code 128 Overview

Many symbologies have a limitation over the length of data while Code 128 is not one of them. It is a variable-length barcode symbology, which allows users to input data at any length.

Symbologies that encode alphabetical and numeric characters are called Alphanumeric Symbologies. And Code 128 is one of the Alphanumeric Symbologies, which encodes alphanumeric characters. Nevertheless, unlike Code 39, Code 128 is able to encode lowercase letters a through z. Besides, one digit of checksum should be included in the Code 128. The checksum is calculated according to the data character and the start character based on modulo 103 calculation.

barcode generator c# wpf, free java barcode generator api, how to read barcode in java, c# free barcode generator, gs1 barcode parser c#, c# barcode reader api

Code 128 is widely used in the internal management of enterprises, the procedure of production, and the barcode systems of logistics control system.

Code 128 Bracode Generation

KeepAutomation.com provides the following different products for different industries requirements.

Code 128 Generator for Office Word - An Office barcode add-in that inserts Code 128 barcode image into Word documents

Code 128 Generator for .NET - .NET Component that generates Code 128 for Windows and Web Applications

Code 128 Generator for Winforms - A windows forms development tool for Code 128 barcode image generation

Code 128 Generator for ASP.NET - An ASP.NET SDK to Code 128 barcode image in ASP.NET projects

Code 128 Generator for Java - Java Class Library that is used for Code 128 bar code image generation in Java

Code 128 Structure

Left Quiet Zone
Start character
Data characters: any length
Checksum: one checksum in modulo 103
Stop character
Termination bar
Right Quiet Zone

In ISO/IEC 15417 specification, the quiet zone should be at least ten times the width of the narrowest bar/space element. It is mandatory at the left and right side of the barcode.

Code 128 Code Sets and Function Characters

To meet more requirements in every walk of life, Code 128 was developed to contain three unique data character code sets: code set A, B and C.

Code set A: ASCII characters 00 to 95 (0-9, A-Z and control codes) and several special characters (CODE B and C, FNC 1-4 and SHIFT)
Code set B: ASCII characters 32 to 127 (0-9, a-z) and some special characters (CODE B and C, FNC 1-4 and SHIFT)
Code Set C: 00-99 (encodes each two digits with one code) and three special characters (CODE A, CODE B and FNC1)

Moreover, using Code A, B, C and Shift characters, Code 128 encodable characters can be changed from one code set to another within a symbol. And, these characters cannot be transmitted by the decoder. In addition, Code 128 is available to be used by GS1 system using FNC1 that enables Code 128 to encode Application Identifier (AI) and some special characters.

Code 128 Check Digit Calculation

Since Code 128 is self-checking, a check digit normally isn't necessary. However, a module 103 checksum digit may be added in applications that require an extremely high level of accuracy. It can be calculated as the following steps:

1.
Retrieve the symbol character value respectively.
2.
Each symbol character position is given a weighting. The start character position is weighted 1. Then, other positions from the beginning on the left with the first symbol character are weighted 1, 2, 3, 4, ..., n.
3.
Multiply each character by its weighting in the barcode string.
4.
Sum the products of calculation in step 3.
5.
The sum of the products is then divided by 103.
6.
The value of the remainder in step 4 is the value of the symbol check character. After that, you should find the corresponding checksum digit according to its ASCII value.

Code 128 & GS1 128 Comparison

Because GS1 128 is the subset of Code 128, there are many similarities between them. Of course they also have some differences. Please see the following table:

Comparison		Code 128	GS1 128
Similarities	Encodable Data	Code Set A Code Set B Code Set C	Code Set A Code Set B Code Set C
	Check Digit Mode	Mode 103	Mode 103
	Code Tpye	Continuous	Continuous
	Symbol Length	Variable	Variable
	Function Characters	FNC 1 FNC 2 FNC 3 FNC 4	FNC 1 FNC 2 FNC 3 FNC 4
Differences	Structure	Left quiet zone Start character Data characters Checksum Stop character Termination bar Right quiet Zone	Left quiet zone Start character Function 1 Symbol Character(FNC1) Data characters Checksum Stop character Termination bar Right quiet zone
Differences	Application	Used extensively worldwide; In many applications where a relatively large amount of data must be encoded in a relatively small amount of space.	Used for goods and palettes in commerce and industry. More than one data field can be encoded using Application Identifiers.