struct sendMsg1 {
  byte errorCheck;//1

  unsigned long dT1;//4
  unsigned long dT2;//4
  unsigned long t;//4
  unsigned long plus[10];//40
};//53

sendMsg1 msg1;
byte copyMsg1[53];

unsigned long time1;
unsigned long time2;
unsigned long time3;
unsigned long time4;

void setup() {
  Serial.begin(1000000);
}

void loop() {
  sensorRead();
  sendMsg1_f();

  //time3 = micros();
  delayMicroseconds(900);
  //time4 = micros();
}

void sensorRead() {
  time3 = micros();

  msg1.t = micros();
  for (unsigned long i = 0; i < 1; i++) {
    memcpy((void*)&(copyMsg1[i*sizeof(sendMsg1)]), (void*)&msg1, sizeof(sendMsg1));
  }

  time4 = micros();
  msg1.dT2 = time4 - time3;
}

void sendMsg1_f() {
  time1 = micros();

  msg1.errorCheck = 0;
  for (int i = 0; i < sizeof(sendMsg1) - 1; i++) {
    msg1.errorCheck += ((byte*)&msg1)[i];
  }
  Serial.write((byte*)&msg1,sizeof(sendMsg1));

  time2 = micros();
  msg1.dT1 = time2 - time1;
}