一 引言使用计算机进行实时控制时,经常碰到需进行遥测、遥控的情况,这时为提高系统的抗干扰能力,除把模拟量信号转变成数字量信号进行传送外,还应使用光电耦合器,在主机系统的 I/O 接口与传送线之间设置电隔离去掉公共地线。经这样配置之后,在一般情况下是能够抑制住干扰,确保系统可靠运行的,但在测、控距离很长,例如几百米或更长时,而且 I. INTRODUCTION When using a computer for real-time control, often encounter the need for telemetry, remote control, then to improve the anti-interference ability of the system, in addition to the analog signal into a digital signal for transmission, but also optocouplers , In the host system I / O interface and set the transmission line between the electrical isolation to remove the public ground. After this configuration, under normal circumstances is able to suppress the interference, to ensure reliable operation of the system, but in the test, the control distance is very long, such as a few hundred meters or longer, and