The Data Matrix code is a well-known, standardized 2D code that was developed in the USA in the 1980s. It is used for permanent marking, for example, in production, automobile construction, chemistry, medicine and in the delivery of goods. The size of the square or rectangular code can be chosen variably. The individual elements are round or square, depending on the manufacturing process. The code consists of 4-5 main components:
- Finder Pattern: two fixed pairs of continuous and interrupted edges, which serve as boundary lines to delimit the outside and are also used as “equalizers” so that the code can be read from every angle.
- Quiet Zone: the quiet zone is around the outside of the code and serves to delimit it from other optical elements in the image.
- Corner that lies opposite the closed edges: is used for quick identification of the code schemes and can be filled in or empty, depending on the scheme.
- Alignment Pattern: Pairwise continuous or interrupted vertical and horizontal lines serve as alignment patterns and simplify image evaluation. They are also used for error correction.
- Data area: it receives the actual binary information of the code.
The data matrix code contains an integrated error correction. The Reed-Solomon algorithm is used for this in the latest standard (ECC200). If the errors in the code are distributed in such a way that 30% of the area is damaged, but the maximum number of damaged code words is not reached, error correction is possible. However, if the maximum number of damaged code words is exceeded, the error correction is no longer functional.
Compared to classic 1D barcodes, the data matrix code can be read out much more reliably. Furthermore, it is more compact and more robust due to the error correction. The code is generated using common identification processes such as ink printing, needle embossing or laser engraving. The process is selected depending on the conditions and requirements in the respective area of use.
Digital cameras are usually used to evaluate the codes. The camera records the information in the code while software evaluates the image and outputs the information on code content and code quality. Many manufacturers offer compact ID scanners for this purpose, which include cameras as well as lighting and evaluation software.