1C31203G01 EMERSON

Long-term transmission interference:In the computer control system,a long line is required for signal transmission,that is,long-term transmission.For high-speed signal transmission lines,that is,in high-frequency signal circuits,how long the wire can be used as a long wire depends on the frequency of the circuit signal.In some cases,a wire of about 1m should be regarded as a long wire.

There are three problems in the transmission of signals in long lines:one is the wave reflection phenomenon that occurs when high-speed changing signals are transmitted in long lines,the second is signal delay,and the third is that long-term transmission will encounter external interference.

长线传输干扰：在计算机控制系统中，现场信号到控制计算机以及控制计算机到现场执行机构，都需要一段较长的线路进行信号传输，即长线传输。对于高速信号传输的线路，即在高频信号电路中，多长的导线可作为长线，取决于电路信号频率的大小，在有些情况下，可能1m左右的线就应作为长线看待。

信号在长线中传输会遇到三个问题：一是高速变化的信号在长线中传输时出现的波反射现象，二是具有信号延时，三是长线传输会遇到外界干扰。