EMS EnergyPlus (DesignBuider) exhaust fan on/off programming control

edit

I am comparing energy consumption of 2 modes of exhaust fan control - proportional (inverter) control and on/off control . I am using DesignBuilder EMS. The proportional inverter control I implemented.

The on/off control I am still trying to program. I have started programming as below. I need another loop to have the following logic, when Co2 level is below 800 ppm, fan speed is zero, once Co2 level reaches 800 ppm , fan speed is maximum until Co2 level reaches 600 ppm, when Co2 level reaches 600 ppm switch off fan (i.e. fan speed zero) until Co2 level is 800 ppm again, When Co2 is 800 ppm switch on fan (at max speed) until Co2 becomes 600 ppm, then switch off fan until Co2 becomes 800 ppm again etc.

Your help will be much appreciated

<ForAllZones>
EnergyManagementSystem:Sensor,
   <LoopZoneVariableName>Air_CO2_Concentration,
   <LoopZoneIDFName>,
   Zone Air CO2 Concentration;

EnergyManagementSystem:Actuator,
   Fan_Air_Mass_Flow_Rate_FIRSTFLOOR_RM210_EXHAUST_FAN,
   FIRSTFLOOR:RM210 EXHAUST FAN,
   Fan,
   Fan Air Mass Flow Rate;
<LoopNextZone>

! extra outputs for viewing in the results viewer
<If BuildingAttribute HourlyOutput = 1 Then>
Output:Variable, *, Zone Air CO2 Concentration, hourly; 
<Endif>
<If BuildingAttribute TimesteplyOutput = 1 Then>
Output:Variable, *, Zone Air CO2 Concentration, timestep; 
<Endif>

EnergyManagementSystem:ProgramCallingManager,
   CO2 Zone Control,
   InsideHVACSystemIterationLoop,
   CO2ZoneControl;

EnergyManagementSystem:Program,
   CO2ZoneControl,
<ForAllZones>
   ! ON/OFF control of intenal mass flow rate
   ! CO2 levels in zone 
   SET ZoneCO2 = <LoopZoneVariableName>Air_CO2_Concentration,
   ! CO2 level giving rise to lowest mass flow rate
   SET ZoneCO2Min = 600,
   ! Lowest mass flow rate
   SET FlowZoneCO2Min = 0.0,
   ! CO2 level giving rise to highest mass flow rate
   SET ZoneCO2Max = 800,   
   ! Highest mass flow rate
   SET FlowZoneCO2Max = 0.28,
   IF ZoneCO2 <= ZoneCO2Min,
      SET OpenFact = FlowZoneCO2Min,
   ELSEIF ZoneCO2 >= ZoneCO2Max,
      SET OpenFact = FlowZoneCO2Max,
<LoopNextZone>
;