void loop() {
   int serialIndex = 0;
   if(Serial.available() > 0){
     while (0 < Serial.available()) {            // loop through all the received bytes
        String bufferString;
        uint8_t bufferInt;
        bufferString = Serial.readStringUntil(',');
        bufferInt = bufferString.toInt();
        serialBuffer[serialIndex] = bufferInt;  // put current index byte in array
        serialIndex ++;                          // add index.
     }
     sendBytes();
   }
   delay(50);
}

void sendBytes(){
    for(int i = 0; i<boards; i++){
//        int i2cIndex = i*12;
//        for(int j = 0; j <12; j++){
//          i2cBuffer[j] = serialBuffer[j+i2cIndex];
//        }
        Wire.beginTransmission(i+1);
        Wire.write(serialBuffer, 12);
        Wire.endTransmission();
    }
}

if(Serial.available() > 0){

if(Serial.available() == 30){