Arduino + UHF RFID KLM900S + Ultrasonic + Servo - [NO DELAY]

/*
  Connections:
  ------------------------------
  Arduino Uno <---> RF-KLM900S
******************************
    3.3V    <--->     EN
    5V      <--->     5V
    GND     <--->     GND
    3       <--->     TTL_R
    2       <--->     TTL_T
  ------------------------------
*/
#include <SoftwareSerial.h>
#include <Servo.h>

int trigPin = 8;
int echoPin = 9;
long distance;
long duration;
int flag = 0;
int flag3min = 0;
Servo servo1;
SoftwareSerial SSerial(2, 3); // RX, TX

int numOfTags = 3;
//Single Read BB    00    22    00    00    22    7E
byte A[] = {0xBB, 0x00, 0x22, 0x00, 0x00, 0x22, 0x7E};

String TagNo[] = {"30 08 33 B2 DD D9 01 40 00 00 00 00",
                  "E2 80 68 94 00 00 50 20 91 08 58 7E",
                  "E2 80 68 94 00 00 50 20 91 08 58 88"
                 };

String TagID_RX = "";
static unsigned long currentTime = 0;
static unsigned long lastTime = 0;
static unsigned long lastTime2 = 0;
int count = 0;

void setup()
{
  SSerial.begin(115200);
  Serial.begin(115200);
  servo1.attach(11);
  servo1.write(0);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  delay(2000);
}

void loop() {
  ultra();
  static String inputString;
  static unsigned long lastCharArrivalTime = 0;

  if (millis() - lastTime > 50 && inputString == "") {
    SSerial.write(A, sizeof(A));
    lastTime = millis();
  }

  if (SSerial.available())
  {
    byte incomingByte = SSerial.read();
    inputString += "0123456789ABCDEF"[incomingByte / 16];
    inputString += "0123456789ABCDEF"[incomingByte % 16];
    inputString += ' ';
    lastCharArrivalTime = millis();
  }

  if (lastCharArrivalTime != 0 && millis() - lastCharArrivalTime >= 10)
  {
    TagID_RX = inputString.substring(24, 59);
    for (int i = 0; i < numOfTags; i++) {
      if (!TagID_RX.compareTo(TagNo[i]) && distance <= 200) {
        Serial.print("Tag No [");
        Serial.print(i + 1);
        Serial.println("] Found.");
        Serial.println("------------------");
        servo1.write(90);
        delay(1000);
        flag = 1;
        flag3min = 0;
        count = 0;
        lastTime2 = millis();
        //delay(180000);// Gate Open Time in (ms), 1000 = 1 Second, 180,000 = 3 Minutes
      }
      else {
        if (count > 50 && flag == 1) {
          if (flag3min == 0) {
            Serial.println("3 min Timer Started !!");
            flag3min = 1;
          }
          currentTime = millis();
          if (currentTime - lastTime2 > 180000) {
            lastTime2 = millis();
            servo1.write(0);
            count = 0;
            flag = 0;
            flag3min = 0;
          }
          //else {
          //  Serial.print((currentTime - lastTime2) / 1000);
          //  Serial.println("/180 [Seconds]");
          //}
          //delay(180000);// Gate Open Time in (ms), 1000 = 1 Second, 180,000 = 3 Minutes
        }
        count++;
        //Serial.println(count);
        //Serial.println((currentTime - lastTime2)/1000);
      }
    }
    inputString = "";
    lastCharArrivalTime = 0;
  }
}

void ultra() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;
  //Serial.println(distance);
}