Time scheduler, real

T18_REAL_SCHEDULER

PROGRAM TEST_T18
   VAR 
        FB : LIB.HVAC.V1_0.T18_REAL_SCHEDULER := (TPGVALUE := [(STARTTIME := 0, STATE := 0),
        (STARTTIME := 370, STATE := 1),
     (STARTTIME := 650, STATE := 3),
     (STARTTIME := 2070, STATE := 8)], 
      EXCEPTIONS := [(STARTTIME := 1000, ENDTIME := 2000, STATE := 3)]);
      DT1:DT;
     REAL1:REAL;
 END_VAR
 DT1:=getlocaltime();
    FB(CURRENTTIME:=DT1, OUT=> REAL1);
END_PROGRAM

LIB\HVAC

V1.0

Time scheduler is a source of a real variable which value changes according to a weekly schedule with maximum 42 events (changes of state). Exception events (exceptions) defined by date, time, and state can be inserted.

The output value is recalculated at 30-second intervals.

The time scheduler compares current date and time with the definition table and sends the actual state to the output. The output is a real value. The time scheduler can be edited from IDE or HMI - LCD display, web interface, touchscreen, SCADA or another client).

Time scheduler is used to specify variable setpoints in time directly. (Use T19_INT_SCHEDULER for multistate output, like switching between Comfort, Standby, and Off, and boolean scheduler to enable plant operation according to a time schedule.)

At the image below, T18 is used to generate a temperature setpoint for an air handling unit. A correction from a room unit (AHU1_TEMP_CORR) is added, and the result is brought to the air supply PI controller.

In the editor, the basic setpoint is set to 18 °C, and the operation hours setpoint is 21 °C: