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传统门禁一般采用8bit/16bit单片机,由于处理速度.I/O接口等资源有限,通常总线结构为RS-485/422方式。其缺陷是:实时性较差.处理速度较慢.导致用户数量受限(一般在5000以下).报警等信息量过大时易造成数据丢失.功能受限制等.无法实现真正的网络功能.其主要是因为RS-485不能跨网段运行.不能在广域网中运行,即使在局域网
The traditional access control generally adopts 8bit / 16bit one-chip computer, due to the processing speed, the resources such as I / O interface are limited, usually the bus structure is RS-485/422 way. Its shortcomings are: poor real-time processing speed is slower, resulting in a limited number of users (generally below 5000), such as alarm and other information is too large, easy to cause data loss, limited functionality, etc., can not achieve true network functions. The main reason is that RS-485 can not run across network segments. It can not operate in a WAN, even in a local area network