RS485、RS232接口设计指南

注 2：文件第一次归档时，“更改理由”、“主要更改内容”栏写“无”。

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目录......................................................................................................................................................1

RS485、RS422 接口设计指南............................................................................................................1

前 言.....................................................................................................................................................2

1 概述...................................................................................................................................................2

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2 RS-485 与 RS-422 性能指标及其标准............................................................................................2

3 RS-485 与 RS-422 器件及材料说明................................................................................................3

4 RS-485 与 RS-422 设计原理............................................................................................................4

4.1.1 RS-485 与 RS -232 电路的区别与优势.....................................................................4

4.1.2 长短连接的判断标准、物理表现与应对措施.........................................................5

4.1.3 RS-485 与 RS-422 典型应用电路与选择方法..........................................................7

4.1.4 485 总线上处理竞争的方法......................................................................................9

4.2 可靠性的设计......................................................................................................................10

4.2.1 网络配置...................................................................................................................10

4.2.6 瞬态保护...................................................................................................................15

4.2.7 其它需要注意的问题...............................................................................................16

参考资料............................................................................................................................................17

RS485、RS422 接口设计指南 CPU 在线配置 Xilinx FPGA 硬件功能模块设计

XX 硬件功能模块设计说明 <1.0 版本号>

目录

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2 RS-485 与 RS-422 性能指标及其标准............................................................................................2

3 RS-485 与 RS-422 器件及材料说明................................................................................................3

4 RS-485 与 RS-422 设计原理............................................................................................................4

4.2 可靠性的设计......................................................................................................................10

1 概述...................................................................................................................................................2

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RS485、RS422 接口设计指南 CPU 在线配置 Xilinx FPGA 硬件功能模块设计

XX 硬件功能模块设计说明 <1.0 版本号>

RS-485 标准最初由电子工业协会（EIA）于 1983 年制订并发布，后由 TIA-通讯工业协会

修订后命名为 TIA/EIA-485-A，习惯地称之为 RS-485。

RS-485 由 RS-422 发展而来，而 RS-422 是为弥补 RS-232 之不足而提出的。为改进 RS-232

通信距离短、速率低的缺点， RS-422 定义了一种平衡通信接口，将传输速率提高到

10Mbps，传输距离延长到 4000 英尺（速率低于 100kbps 时），并允许在一条平衡线上连接

最多 10 个接收器。RS-422 是一种单机发送、多机接收的单向、平衡传输规范，为扩展应用

范围，随后又为其增加了多点、双向通信能力，即允许多个发送器连接到同一条总线上，同

RS-485 作为一种多点、差分数据传输的电气规范现已成为业界应用最为广泛的标准通信

接口之一。这种通信接口允许在简单的一对双绞线上进行多点、双向通信、它所具有的噪声

抑制能力、数据传输速率、电缆长度及可靠性是其他标准无法比拟的。正因为此，许多不同