Sending array from CSV to Python to Arduino

For my project I am trying to send over an array of three values from a CSV to Python and from there to Arduino.

In this code I send over one value to Arduino and then back to Python to verify if it is working. But In Python I am not receiving anything back. Am I sending over the values from Python to Arduino in the right data type? Maybe some other things I am overlooking?

Python code:

import serial
import struct
import time
import csv

csv_file = open('/home/ko/Downloads/Buzzard_600_2020-04_all_data_with_wind_only flight-for-python.csv')
csv_reader = csv.reader(csv_file, delimiter=';')

i=0

temp = 0

arduino = serial.Serial('/dev/ttyACM0', 115200, timeout=.1)

# let it initialize
time.sleep(2)


def conversion(k):
    kfloat = float(k)
    kint = int(kfloat)
    return kint


# bird, date_time, longitude, latitude, altitude, pressure temperature satellites_used    gps_fixtime    positiondop    h_accuracy v_accuracy x_speed    y_speed    z_speed    speed_accuracy location   userflag   speed_3d   speed_2d   direction  altitude_agl   wind_direction (degrees)   wind_speed (km/h)

for row in csv_reader:
    bird, datetime, longitude, latitude, altitude, pressure, temp, satellites, gpsfixtime, positiondop, h_accuracy, v_accuracy, x_speed, y_speed, z_speed, speed_accuracy, location, userflag, speed_3d, speed_2d, direction, altitude_agl, wind_direction, wind_speed, no = row

    tempint = conversion(temp)
    altitudeint = conversion(altitude)
    wind_directionint = conversion(wind_direction)
    wind_speedint = conversion(wind_speed)

    arduino.write(struct.pack('>BBB', tempint,wind_speedint,altitudeint))
    #arduino.write(bytes(altitude, 'utf-8'))
    #data = arduino.readline()
    print("---------------------")
    #print(i)
    print("temp_int=")
    #print(tempint)
    #print("altitude_map=")
    #print(altitudemap)
    #print("wind_speed_map=")
    #print(wind_speedmap)
    #arduino.write(bytes(tempmap))
    #arduino.write(tempint)
    #arduino.write (tempint)
    #time.sleep(1)
    data = arduino.readline()
    time.sleep(1)
    #print (tempint)
    print (data)
    time.sleep(1)
    i = i + 1
    time.sleep(3)

Arduino code:


#define USE_SERIAL  Serial
int incoming[3];
int outVal1 = 0;
int outVal2 = 0;
int outVal3 = 0;

void setup() {
  USE_SERIAL.begin(115200);
  Serial.setTimeout(1);
}

void loop()
{
  while (!Serial.available() >= 3) {
    //fill array
    for (int i = 0; i < 3; i++) {
      incoming[i] = Serial.readString(). toInt ();
      outVal1 = incoming[0];
      //outVal2 = incoming[1];
      //outVal3 = incoming[2];
      Serial.print (outVal1);
      delay (1000);
    }
  }
}

could you give an example of the CSV data?
try running the Arduino code without the Python host
type sample data into the serial monitor and see what replies you get
once it works as expected try it with the python