struct ValveType {
  unsigned long LastMillis = 0;
  unsigned long interval   = 150;
  unsigned long onTime     = 150;
  unsigned long offTime    = 400;
  unsigned long offSet     = 0;

  boolean       isOn = false;
  int           Pin;
};

const int NoOfValves = 2;

ValveType Valve[NoOfValves];

void SwitchIntervalOfValve(int No){
    if (Valve[No].isOn) Valve[No].interval = Valve[No].onTime + Valve[No].offSet;
                  else  Valve[No].interval = Valve[No].offTime+ Valve[No].offSet;
}


void SetValve(int No, int State) {
  Valve[No].isOn = State;
  SwitchIntervalOfValve(No);
  digitalWrite(Valve[No].Pin, Valve[No].isOn);
}

void InitValve(int No, int State, unsigned long offset = 0) {
  Valve[No].offSet = offset;
  SetValve(No, State);
}

void SwitchValveNo(int No, unsigned long now) {
    if (now - Valve[No].LastMillis > Valve[No].interval) {
      Valve[No].LastMillis = now;
      Valve[No].isOn = !Valve[No].isOn;
      SetValve(No, Valve[No].isOn);
    }
}

void SwitchValves() {
  unsigned long now = millis();
  for (int i = 0; i < NoOfValves; i++ ) SwitchValveNo(i, now);
}

void setup() {
  Serial.begin(115200);
  // Just a quick initialization
  for (int i = 0; i < NoOfValves; i++ ) {
    Valve[i].Pin = 9 + i; // Only valid for max. 5 "Valves" = Leds, as 9 + 4 = 13 (Pin 13)
    pinMode(Valve[i].Pin, OUTPUT);
  }
  InitValve(0,LOW,0);
  InitValve(1,LOW,200);

}

void loop() {
  SwitchValves();
}