任何把计算机使用到控制现场生产过程的用户,都必须有它自己的用户设备或叫工业外围设备,也就是通常所说的“接口设备”。这种设备负责把现场操作的各种过程变量转换为计算机能够接收的数字量,交给计算机处理,或把计算机送出的数字量变为现场的各种实际动作,如阀门的开闭,电机的快慢,指示灯的亮暗等等。为了与计算机系统设备相区别,软件设计人员就称这些设备为用户设备。它们通常有开关量输入、开关量输出、模拟量输入、模拟量输出以及操作控制台等。 Any user who uses a computer to control the on-site production process must have its own user equipment or industrial peripherals, also known as “interface devices.” This equipment is responsible for the operation of the various process variables into the computer can receive the digital, to the computer processing, or put the digital computer sent to the scene a variety of practical actions, such as the valve opening and closing, the motor speed , Light and dark lights and so on. To differentiate from computer system equipment, software designers call these devices user devices. They usually have digital inputs, digital outputs, analog inputs, analog outputs and operating console.