MU-TAIL01
数字控制器接收来自传感器的电子信号，将电子信号转换为数字脉冲（值），并对这些值执行数学运算。控制器将输出值重新转换为信号，以操作执行器。控制器以设定的时间间隔对数字数据进行采样，而不是连续读取数据。这种采样方法称为离散控制信号。如果正确选择数字控制器的采样间隔，离散输出变化将提供均匀且不间断的控制性能。图20比较了模拟和数字控制信号。数字控制器根据一组测量的控制变量和一组给定的控制算法定期更新过程。控制器完成整个计算，包括控制算法，并向执行器发送信号。在许多较大的商业控制系统中，电子气动传感器将电输出转换为可变压力输出，用于终控制元件的气动驱动。

The digital controller receives electronic signals from sensors, converts the electronic signals to digital pulses (values), and performs mathematical operations on these values. The controller reconverts the output value to a signal to operate an actuator. The controller samples digital data at set time intervals, rather than reading it continually. The sampling method is called discrete control signaling. If the sampling interval for the digital controller is chosen properly, discrete output changes provide even and uninterrupted control performance. Figure 20 compares analog and digital control signals. The digital controller periodically updates the process as a function of a set of measured control variables and a given set of control algorithms. The controller works out the entire computation, including the control algorithm, and sends a signal to an actuator. In many of the larger commercial control systems, an electronic-pneumatic transducer converts the electric output to a variable pressure output for pneumatic actuation of the final control element.