n Timer Function OperationThe timer function switches on when the timer function input closes for longer than the value set to b4-01. The timer functionswitches off when the timer function input is open for longer than the value set to b4-02. Figure 1.14 illustrates the timerfunction operation:b4-01 b4-02 b4-01 b4-02Multi-function Contact On (Closed)Off (Open)On (Closed)Off (Open)Multi-function ContactOutput: Timer FunctionInput: Timer Function ON ONON ON（H1-□□=18)（H2-□□=12)Figure 1.14 Timer Operationu b5: PI ControlThe drive has a built-in Proportional + Integral (PI) controller that uses the difference between the target value and the feedbackvalue to adjust the drive output frequency to minimize deviation and provide accurate closed loop control of system variablessuch as pressure or temperature.n P ControlThe output of P control is the product of the deviation and the P gain so that it follows the deviation directly and linearly. WithP control, only an offset between the target and feedback remains.n I ControlThe output of I control is the integral of the deviation. It minimizes the offset between target and feedback value that typicallyremains when pure P control is used. The integral time (I time) constant determines how fast the offset is eliminated.n PI OperationTo better demonstrate PI functionality, the diagram below illustrates how the PI output changes when the PI input (deviation)jumps from 0 to a constant level.PI inputI controlPI OutputTimePI outputTimeP controlFigure 1.15 PI Operationn Using PI ControlApplications for PI control are listed in the following table.Application Description Sensors UsedSpeed Control Machinery speed is fed back and adjusted to meet the target value. Synchronous control isperformed using speed data from other machinery as the target value TachometerPressure Maintains constant pressure using pressure feedback. Pressure sensorFluid Control Keeps flow at a constant level by feeding back flow data. Flow rate sensorTemperatureControl Maintains a constant temperature by controlling a fan with a thermostat. Thermocoupler,Thermistorn PI Setpoint Input MethodsThe PI setpoint input depends on the PI function setting in parameter b5-01.1.2 b: ApplicationYASKAWA SIEP YAIZ1U 03B YASKAWA AC Drive – Z1000 Programming Manual 371 Parameter Details
