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1) Scope of application Bar code technology is applied in different occasions, and different bar code readers should be selected. For example, to develop a bar code warehouse management system, it is often necessary to frequently count laboratories in the warehouse. Correspondingly, the bar code reader is required to be portable and can temporarily store the inventory information instead of being limited to use in front of the computer. It is better to choose a portable bar code reader. Suitable. When using a barcode collector on a production line, it is generally necessary to install a barcode reader in some fixed positions on the production line, and the parts produced are more suitable for barcode readers, such as laser gun type, CCD scanner, etc. In the conference management system and enterprise attendance system, a card-type or slot-type barcode reader can be selected. The person who needs to sign in will insert the barcode-printed certificate into the reader slot, and the reader will automatically scan and give a reading success signal. This enables real-time automatic check-in. Of course, for some special occasions, special bar code reader devices can also be developed to meet the needs.

2) Decoding range The decoding range is another important indicator for choosing a barcode reader. At present, the decoding range of barcode readers produced by various companies is very different. Some readers can recognize several code systems, and some readers can recognize more than a dozen code systems. When developing a bar code application system, select the corresponding code system. At the same time, when configuring a bar code reader for the system, the reader is required to have the function of correctly deciphering the symbols of this code system. In logistics, UPC/EAN code is often used. Therefore, when developing a shopping mall management system, when selecting a reader, it should be able to read UPC/EAN code. In the post and telecommunications system, China currently uses the matrix 25 code. When selecting a reader, the symbol of the code system is guaranteed.

3) Interface capability There are many application fields of barcode technology, and there are many types of computers. When developing an application system, the hardware system environment is generally determined first, and then a barcode reader suitable for the environment is selected. This requires the interface mode of the selected reader to meet the overall requirements of the environment. There are two interface modes for general barcode readers: A. Serial communication. This communication method is generally used when a small and medium-sized computer system is used, or when the data collection site occupies a long distance from the computer. For example, in the enterprise attendance management system, the computer is generally not placed at the entrance and exit, but in the office, so as to grasp the attendance situation in time. B. Keyboard emulation is an interface method that transmits the barcode information collected by the reader to the computer through the keyboard port of the computer, and is also a commonly used method. At present, the keyboard methods such as XKAT are commonly used in IBM/PC and its compatible machines. The keyboard port of the computer terminal also has various forms. Therefore, if you choose keyboard emulation, you should pay attention to the type of computer in the application system, and pay attention to whether the selected reader can match the computer.

4) Requirements for parameters such as first reading rate The first read rate is a comprehensive indicator of barcode readers, which is related to the printing quality of barcode symbols, the design of code selectors and the performance of photoelectric scanners. In some application fields, a hand-held bar code reader can be used to control the repeated scanning of bar code symbols by humans. At this time, the requirements for the first read rate are too strict, and it is only a measure of work efficiency. In industrial production, self-warehousing and other applications, a higher first read rate is required. The barcode conforming carrier moves on the automatic production line or conveying belt, and there is only one chance to collect data. If the first reading rate does not reach 100%, the phenomenon of data loss will occur, resulting in serious consequences. Therefore, in these application fields, bar code readers with high first read rate, such as CCD scanners, should be selected.

5) Resolution When selecting a device for correct detection of the width of the narrowest bar read in, the barcode density used in the application selects a reading device with the appropriate resolution. In use, if the resolution of the selected device is too high, the system will be more seriously affected by smudges and de-inking on the bars.

6) Scan Properties Scanning attributes can be subdivided into scanning depth of field, scanning width, scanning speed, one-time recognition rate, bit error rate, etc. Scanning depth of field refers to the difference between the farthest distance that the scan head is allowed to leave the barcode surface and the closest point distance that the scanner can approach the barcode surface under the premise of ensuring reliable reading, that is, the effective working range of the barcode scanner. Some barcode table scanning devices do not give the scanning depth of field index in the technical indicators, but give the scanning distance, that is, the shortest distance that the scanning head is allowed to leave the barcode surface. Scan width refers to the physical length of barcode information that can be read by the scanning beam at a given scanning distance. The scanning speed refers to the frequency of the scanning light on the scanning track. The one-time recognition rate represents the ratio of the number of tags read by a person scanned for the first time to the total number of scanned tags. The test index of one-time recognition rate is only applicable to the hand-held light pen scanning recognition method. If using the acquired signal is repeated. The bit error rate is equal to the ratio of the total number of false identifications. For a bar code system, the bit error rate is a more serious problem than the low one-time recognition rate.

7) Barcode symbol length Bar tri-symbol length is a factor that should be considered when choosing a reader. Due to the influence of manufacturing technology, some photoelectric scanners specify the maximum scanning size, such as CCD scanners and moving beam scanners. In some application systems, the length of the barcode symbol is randomly changed, such as the index number of the book, the length of the barcode symbol on the product package, etc. In variable-length applications, the influence of barcode symbol length should be noted when selecting a reader. 8) The price of the reader Due to the different functions of the readers, the prices are also inconsistent. Therefore, when selecting the readers, pay attention to the performance-price ratio of the products, and should meet the requirements of the application system and the price should be lower as the selection principle. 9) Special functions It is necessary to enter from several entrances and connect several readers to one computer, so that the readers at each entrance can collect information and send them to the same computer. Therefore, the readers are required to have networking functions to ensure that the computer can accurately receive information and timely deal with. When the application system has special requirements for the barcode reader, special selection should be made.