Notes on selecting code readers. Barcode size adaptation: pay attention to the module width, minimum readable height and maximum readable width of the barcode. The smaller the module width, the higher the resolution requirements of the code reader. If the code reader cannot recognize the minimum height or exceed the maximum width, it will cause reading failure. Content data bit matching: Different barcode types (one-dimensional codes, QR codes, etc.) and encoding standard data bit lengths are different. It is necessary to ensure that the code reader can correctly decode the barcode type and content data bits in the application, especially complex barcodes, and the decoding success rate and speed must be ensured. Code reading speed evaluation: In industrial production, according to the moving speed of the assembly line item, select enough code readers (measured by FPS read per second). For example, some high-speed pipelines require the code readers to reach more than 600FPS. Communication interface compatibility: According to the application scenario, select communication interfaces compatible with external devices, such as Ethernet, USB, RS-232, TCP/IP, etc. Remote monitoring and data upload scenarios are suitable for Ethernet or TCP/IP interfaces, small device connections or temporary use scenarios, and USB interfaces are more convenient.