The I/O bus is connected to the controller.In the 1980s,due to the low computing power of the controller,the DCS in the 1980s separated the tasks of the controller in order to increase the number of I/O points.There are actually three types of controllers.Namely:controllers,analog data collectors and logic operators that complete closed-loop operations.They have their own I/O buses,and the I/O buses of various DCSs are different.If fast speed is required,it is best to use a parallel bus.Generally,the serial bus is used more.In particular,there are many RS485 buses,and the number of I/O points of the analog data collector and logic operator can be more.
I/O总线和控制器相连。80年代的DCS由于控制器的运算能力不强，为了增加I/O点数，把控制器的任务分开，实际上是有三种类型的控制器。即：完成闭环运算的控制器、模拟量数据采集器和逻辑运算器。它们分别有自己的I/O总线，各种DCS的I/O总线各不相同。如果要求快速，最好采用并行总线。一般采用串行总线比较多。尤其是RS485总线较多，模拟量数据采集器和逻辑运算器的I/O点数可以多一些。
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