Fingerprint scanner with Arduino UNO WiFi Rev2

[s21327]

Hi,
I am in the process of doing my thesis for my studies. My topic is biometric login to IT systems.

I am making a physical module for collecting fingerprints from users based on the Arduino UNO WiFi Rev2 microcontroller and Waveshare UART Fingerprint Reader. Unfortunately, I have a problem with communication between these two elements.

According to the documentation of the fingerprint scanner, commands should be sent via the UART port. As an example, I will use the command to get the total number of users (point 2.6 in the communication protocol file).
I send 8 bytes {0xF5, 0x09, 0x00, 0x00, 0x00, 0x00, 0x09, 0xF5} to the serial port, unfortunately I do not receive any response from the module. I tested the connection on HardwareSerial Serial1 (pin 0, pin 1) and SoftwareSerial (pin 2, pin 3) and (pin 10, pin 11).

I also tested the efficiency of the scanner itself by connecting it via USB-to-UART module to the computer and using the software provided by the producer. The scanner responds correctly.

I would be very grateful for any hint!

Fingerprint Scanner: UART Fingerprint Reader - Waveshare Wiki
Scanner communication protocol: 注意： (waveshare.com)

I am attaching a sample program, the connections I use in it are:

FINGERPRINT SCANNER	ARDUINO UNO WIFI REV2
VCC	5V
GND	GND
TXD	0
RXD	1

void setup() 
{
  Serial.begin(9600);
  Serial1.begin(19200);

  Serial.println("===== START =====");
  userCount();
  Serial.println("===== END =====");
}

void loop() {}

void userCount()
{
  byte cmd[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
  byte checkSum = 0;

  cmd[0] = 0xF5;
  cmd[1] = 0x09;
  cmd[7] = 0xF5;

  checkSum = 0;
  for(int i=1; i<6; i++)
  {
    checkSum = checkSum^cmd[i];
  }
  cmd[6] = checkSum;

  Serial.println("Sent:");
  for(int i=0; i<8; i++)
  {
    Serial1.write(cmd[i]);
    Serial.print(cmd[i]);
    Serial.print(' ');
  }

  Serial.println();
  delay(10000);

  Serial.println("Received:");
  byte temp=0;
  while(Serial1.available()>0)
  {
    temp = Serial1.read();  
    Serial.print(temp);
    Serial.print(' ');
  }
}