We can control single loop by PID-controller which has many methods for find the value to tuning. First, we will need to know what we control in system from p&id. Then, the simatic S7 program connects with system in order to control single loop. Wiring diagram is very important because if the wiring faults, the system may not work and may be dangerous, too. The MATLAB program helps to calculate the value of gain and and τ_I. Moreover, it also helps to see the trend of system. The result of tuning, it makes the value of PV according to the value of SP due to control of PI-controller. We don’t use D-controller because the system of level must be change slowly in order to accurate result.