Communication between 2 H18(similar to H10) bluetooth module

[loyojo]

Hi, I just started to use Arduino and in our project, we need to establish communication between 2 Bluetooth modules. We are using HM18 module. However, the mySerial.available() always returns 0 although the 2 Bluetooth could connect automatically (light stop blinking).
Code for sending

#include <SoftwareSerial.h>
SoftwareSerial mySerial(10,11);
int trigPin = 6;
int echoPin = 7;
int ledp=8;

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(19200);
  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

}

void loop() { // run over and over
  long duration, distance;
  digitalWrite(trigPin,HIGH);
  delayMicroseconds(1000);
  digitalWrite(trigPin, LOW);
  duration=pulseIn(echoPin, HIGH);
  distance =(duration/2)/29.1;
//  Serial.print(distance);
//  Serial.println("CM");
  delay(10);
 
  if((distance<=20)) 
  {
    digitalWrite(ledp,HIGH);
    mySerial.write(111);
    //Serial.println("distance");
    Serial.println("distance");
    delay(500);
  }
  else{
    digitalWrite(ledp,LOW);
  }
    
}

code for receiving

#include <SoftwareSerial.h>
SoftwareSerial mySerial(10,11);
int ledp=8;
int buz=9;
int timesRepeat=0;

void setup() {
  pinMode(ledp,OUTPUT);
  pinMode(buz,OUTPUT);
  // Open serial communications and wait for port to open:
  Serial.begin(19200);
  
  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
  mySerial.println("Hello, world?");
}

void loop() { // run over and over 

  if (mySerial.available()>0) {
    delay(1);
    int data = mySerial.read();//read()readStringUntil('\n')
    //Serial.println("mySerialavailable");  
    //Serial.println(data);
    //if alert condition match
    if(timesRepeat!=0){ 
      timesRepeat--;
      digitalWrite(ledp,HIGH);
      delay(50);
      digitalWrite(ledp,LOW);
    }
    else{
      if(data==111){
          Serial.println("alert");
          //digitalWrite(ledp,HIGH);
          timesRepeat=20;
      }
    }
  }
}

I've been working on this for hours but still no clue,,,
Thanks for the help in advance!