概述：本范例演示水箱水位的过程模拟。过程中添加噪声、阀门死区、滞后和死区时间。液位控制器调整水箱的输入。开/关阀作为一个排水口，可点击操作。该s阀表示过程负载变化。该VI可以在自动、手动控制间切换。
操作步骤：
1.运行VI。
2.闭环中检查PID控制器，跟踪设定值。
3.改变设定值，检查控制器跟踪新设定值。
4.切换阀门HV 102（单击阀门符号），对系统应用干扰。可观察到控制器从变化中恢复。
5.改变PID增益，并观察是否能在稳态下提高其性能。
6.切换到手动模式并观察是否可以通过改变阀门LVC 101来控制水位。
7.单击停止按钮停止VI。(Summary: this example demonstrates the process simulation of water tank level. Add noise, valve dead zone, lag and dead time. The level controller adjusts the input of the water tank. The opening / closing valve is a drainage outlet and can be operated by clicking. The S valve indicates the change of the load of the process. The VI can be switched between automatic and manual control.　　　　　　Operation steps:　　　　　　1. run VI.　　　　　　2. the PID controller is checked in the closed loop, and the set value is tracked.　　　　　　3. change the set value and check the controller to track the new setting value.　　　　　　4. switch the valve HV 102 (click the valve symbol) to interfere with the system. The controller can be observed to recover from the change.　　　　　　5. change the gain of PID and observe whether it can improve its performance under steady state.)