PFSK151 3BSE018876R1用于控制发送驱动器

PFSK151 3BSE018876R1用于控制发送驱动器

RS485接口组成的半双工网络，一般是两线制，多采用屏蔽双绞线传输，这种接线方式为总线式拓扑结构在同一总线上多可以挂接32个结点。我们知道，初数据是模拟信号输出简单过程量，后来仪表接口是RS232接口，这种接口可以实现点对点的通信方式，但这种方式不能实现联网功能，随后出现的RS485解决了这个问题。为此本文通过问答的形式详细介绍RS485接口。

什么是RS-485接口？它比RS-232-C接口相比有何特点？



答：由于RS-232-C接口标准出现较早，难免有不足之处，主要有以下四点：
（1）接口的信号电平值较高，易损坏接口电路的芯片，PFSK151 3BSE018876R1又因为与TTL电平不兼容故需使用电平转换电路方能与TTL电路连接。




（2）传输速率较低，在异步传输时，波特率为20Kbps。



（3）接口使用一根信号线和一根信号返回线而构成共地的传输形式，这种共地传输容易产生共模干扰，所以抗噪声干扰性弱。

PFSK151 3BSE018876R1用于控制发送驱动器

A half duplex network composed of RS485 interfaces is generally a two wire system, often using shielded twisted pair transmission. This wiring method is a bus topology structure, which can connect up to 32 nodes on the same bus. We know that the initial data was analog signal output with simple process variables, but later the instrument interface was RS232, which can achieve point-to-point communication, but this method cannot achieve networking function. Subsequently, RS485 solved this problem. This article provides a detailed introduction to the RS485 interface through question and answer format.



What is the RS-485 interface? What are its characteristics compared to the RS-232-C interface?




Answer: Due to the early emergence of the RS-232-C interface standard, there are inevitably shortcomings, mainly including the following four points:

(1) The signal level value of the interface is relatively high, which can easily damage the chip of the interface circuit. PFSK151 3BSE018876R1 needs to use a level conversion circuit to connect to the TTL circuit because it is not compatible with the TTL level.





(2) The transmission rate is relatively low, with a baud rate of 20Kbps during asynchronous transmission.




(3) The interface uses a signal line and a signal return line to form a common ground transmission form, which is prone to common mode interference and therefore has weak noise immunity.

PFSK151 3BSE018876R1用于控制发送驱动器
 

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