두개 초음파센서를 연결해서 사용할려고 합니다. 한 개 초음파센서만 출력이 되고 하나는 작동이 안되는데요

3핀짜리 초음파센서를 사용합니다.... 봐주시고 수정좀 부탁드려요....

#include

// TX_PIN is not used by the sensor, since that the it only transmits!
#define PING_RX_PIN 7
#define PING_TX_PIN 7

#define PING_RX_PIN2 8
#define PING_TX_PIN2 8

SoftwareSerial mySerial(PING_RX_PIN, PING_TX_PIN);

long inches = 0, mili = 0, cm = 0;
byte mybuffer[4] = {0};
byte bitpos = 0;

SoftwareSerial mySerial1(PING_RX_PIN2, PING_TX_PIN2);

long inches1 = 0, mili1 = 0, cm1 = 0;
byte mybuffer1[4] = {0};
byte bitpos1 = 0;

void setup() {
  Serial.begin(9600);
  mySerial.begin(9600);
  mySerial1.begin(9600);
}

void loop() {
 bitpos = 0;
  while (mySerial.available())
  {
    // the first byte is ALWAYS 0xFF and I'm not using the checksum (last byte)
    // if your print the mySerial.read() data as HEX until it is not available, you will get several measures for the distance (FF-XX-XX-XX-FF-YY-YY-YY-FF-...). I think that is some kind of internal buffer, so I'm only considering the first 4 bytes in the sequence (which I hope that are the most recent! :D )
    if (bitpos < 4)
    {
      mybuffer[bitpos++] = mySerial.read();
    }
    else break;
  }
  mySerial.flush(); // discard older values in the next read

  mili = mybuffer[1]<<8 | mybuffer[2]; // 0x-- : 0xb3b2 : 0xb1b0 : 0x--
  inches = 0.0393700787 * mili;
  cm = 2.54 * inches;
 
  Serial.print("Serial =");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
 
  delay(300);

  bitpos1 = 0;
  while (mySerial1.available()) {
    // the first byte is ALWAYS 0xFF and I'm not using the checksum (last byte)
    // if your print the mySerial.read() data as HEX until it is not available, you will get several measures for the distance (FF-XX-XX-XX-FF-YY-YY-YY-FF-...). I think that is some kind of internal buffer, so I'm only considering the first 4 bytes in the sequence (which I hope that are the most recent! :D )
    if (bitpos1 < 4) {
      mybuffer1[bitpos1++] = mySerial1.read();
    } else break;
  }
  mySerial1.flush(); // discard older values in the next read

  mili1 = mybuffer1[1]<<8 | mybuffer1[2]; // 0x-- : 0xb3b2 : 0xb1b0 : 0x--
  inches1 = 0.0393700787 * mili1;
  cm1 = 2.54 * inches1;
 
  Serial.print("mySerial1 =");
  Serial.print(cm1);
  Serial.print("cm");
  Serial.println();
 
  delay(300);
}