How to synchronize ultrasonic sensor speed and serial baudrate?

Hello people, I wonder who can point me in the right direction here: I have an LV-Maxsonar-EZ3, wired and working on an arduino pro mini of 3.3v.

The problem: As you see in the code below, the serial Port is initiated at 9600, however when reading from the serial monitor or from another application at the same baudrate, either gibberish or an error (on Processing) comes out. So I tried changing the baudrate in the serial monitor and when I got to 19200, voilá, the values can be read and they are ok. Why does that happen?

I always thought that the speed on both sides should be the same....

Now becomes the problem, because the sensor should work together with other sensors on the same arduino and if I read at 19200 I'll get gibberish input for all the others that don't show this synchronicity problem. Any workaround? Can I specify some sort of speed for the sensor?

Exacly the same issue happens to me using another ultrasonic sensor HC-SR04 on a 5v pro mini, so I guess it's not an arduino Problem but something more basic related to ultrasonic sensors

Thanks a lot

code:

const int pwPin1 = 7;
long pulse1, sensor1;

void setup () {
  Serial.begin(19200);
  pinMode(pwPin1, INPUT);
}

void read_sensor(){
  pulse1 = pulseIn(pwPin1, HIGH);
  sensor1 = pulse1/147;
}

//This section of code is if you want to print the range readings to your computer too remove this from the code put /* before the code section and */ after the code
void printall(){         
  Serial.print("S1");
  Serial.print(" ");
  Serial.print(sensor1);
  Serial.println(" ");
}

void loop () {
  read_sensor();
  printall();
  delay(50); // This delay time changes by 50 for every sensor in the chain.  For 5 sensors this will be 250
}

input from sensor on serial monitor at 9600 baud: 4 TDªÄª!ª ªÄ!ªª$ª ªÄª$ªÈÖÄ( ?Äā$ªÄ$TÄXÄ?!þĪ$ª?¡þ?Mþ?!þDHþTdLþLþ$ª ª!TÄÄTD?ÖÄX ÄT  ā$ÄX PÄ DÄÄ!ÄXÄXÄTÄ$ÄXÄD ÄTDÄX $$ÄDÄÄTÄPÈÕÄTÄ TÄT$TÄ$Ä(ÄTÄÄTÄX TTÄTÄTāÈÆÄT$ $āÄ$ÄÄÄTÄ!XÄX$ÄTÄXÄ $ÄT ÄPÄTDÄT ÄXÈÆdTÄT$?!$?????ªÄT?ªª?)?!T?T?dª T$ÿ?,Äÿ?Tª ªÄÿĪ$ÿ$T$ÿÄS?T?$ª

input from sensor on serial monitor at 19200 baud: S1 32 S1 30 S1 31 S1 31 S1 31 S1 31 S1 31 S1 30 S1 30 S1 20 S1 31 S1 294 ...

A 3.3V Pro Mini board runs with a crystal of 8MHz. Therefor, it should also have a bootloader for 8MHz and you should select the Pro Mini 8MHz.

I think it has the right bootloader of 8MHz, but you selected an 16MHz board to compile.

Indeed, even simpler than I thought... It is a matter of choosing the right bootloader... The confusion was brought by working with two almost identical but different boards. Thanks!