Code 128 Barcode Scanner

What is Code 128?

Code 128 is a one-dimensional barcode format that encodes all 128 standard ASCII symbols, including uppercase and lowercase letters, numeric digits, and special characters. It is standardized in ISO/IEC 15417 and features three character subsets (A, B, and C), each optimized for a specific data type.

Code 128 offers high density and flexibility. Each symbol can represent a large amount of information in a small space. It is ideal for logistics, warehousing, and other applications that require compact, variable-length barcodes.

GS1-128 barcodes combine the Code 128 symbology with GS1 application identifiers.

Structure and components

Code 128 barcodes consist of the following key components:

1. Quiet zones: Blank areas on both sides of the barcode that ensure proper detection and readability.
2. Start character: A unique 11-module pattern (3 bars and 3 spaces) that indicates which character set (A, B, or C) will be initially used.
3. Data characters: The main content section where information is encoded. Each character consists of 11 modules (3 bars and 3 spaces). Code 128 encodes all 128 ASCII characters and switches between sets A, B, and C for optimal efficiency.
4. Check character: A mandatory verification element calculated using a weighted modulo-103 checksum. It ensures data integrity by providing error detection.
5. Stop character: A distinct 13-module pattern (4 bars and 3 spaces) that marks the barcode’s end.

Despite its name, it doesn’t contain 128 distinct symbols – instead, it achieves full ASCII coverage by switching between sets A and B, while set C specializes in encoding digit strings efficiently. Code 128 in fact consists of 108 symbols (103 data symbols, 3 start symbols, and 2 stop symbols).

The table below shows which code set supports which characters (excluding the barcode’s function codes):

Error detection

Code 128 provides error detection through a modulo 103 check digit, which is added before the stop symbol. Here’s how it works:

1. The scanner reads the encoded data and calculates a checksum.
2. This is compared with the check digit in the barcode.
3. If both check digits match, the data is considered valid.
4. If they don’t match, the scan is rejected as an error.

While Code 128 allows scanners to detect errors effectively, it does not have built-in error correction capabilities.

Applications of Code 128 barcodes

Logistics and shipping

Code 128 barcodes are widely used for real-time package tracking and automated sorting in shipping operations across global supply chains.

Inventory management

Code 128 barcodes simplify inventory management by encoding comprehensive product data, including serial numbers, batch codes, and production dates.

Manufacturing

In production environments, Code 128 is used to ensure accurate component tracking and assembly verification while maintaining complete product traceability.

Healthcare

Healthcare facilities employ Code 128 for patient safety systems. The symbology allows precise tracking of medication, medical equipment, lab specimens, and patient records.

Advantages of Code 128 barcodes

• High data density: Encodes large amounts of information in a compact format.
• Full ASCII support: Represents standard ASCII symbols, including uppercase, lowercase, and special characters.
• Versatile encoding: Efficiently handles numeric, alphanumeric, and control codes through its three subsets.
• Simple printing: Barcodes can be created using regular printers, rather than requiring specialized equipment, unlike older barcode formats which need thermal printers for reliable scanning.

Why choose the Scanbot SDK for Code 128 barcode scanning?

The Scanbot Barcode Scanner SDK is tailored to decode Code 128 barcodes quickly and accurately, even in demanding scenarios.

What sets us apart:

• Exceptional performance: Reliably decodes even damaged, low-contrast or distorted barcodes.
• High-speed scanning: Reads Code 128 barcodes in as little as 0.04 seconds.
• Cross-platform compatibility: Easily integrate with Android, iOS, cross-platform, web, Windows, and Linux platforms.
• Customizable UI: Customize the ready-to-use components to match your app or website design.
• Privacy-first: Operates offline for complete data security.

Whether your use case involves Code 128, QR codes, or any other barcode, the Scanbot SDK delivers the accuracy, speed, and reliability you need to succeed.

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