LCD I2C Uno

Hello
I have a problem with my Arduino Uno connected to LCD by I2C converter. When I am connecting my Arduino with 16x2 LCD normally (by RS R/W EN etc) its work fine but when im trying connect it by I2C converter my LCD is light on but it doesnt shown any letters. I can change contrast so i dont think that converter is broken. Even the I2C scanner is detecting nothing (No I2C devices found). I have Arduino Uno R3 so i tried connecting SDA ->A4, SCL -> A5 and SDA->SDA, SCL->SCL (Uno R3 have output SCL and SDA pins).My libraries are imported properly (my code is compile without errors) I would be gratefull for any help. I am adding code which i used to.

#include <Wire.h>
 
 
void setup()
{
  Wire.begin();
 
  Serial.begin(9600);
  Serial.println("\nI2C Scanner");
}
 
 
void loop()
{
  byte error, address;
  int nDevices;
 
  Serial.println("Scanning...");
 
  nDevices = 0;
  for(address = 1; address < 127; address++ )
  {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
 
    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");
 
      nDevices++;
    }
    else if (error==4)
    {
      Serial.print("Unknow error at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");
 
  delay(5000);           // wait 5 seconds for next scan
}
//kod ze strony botlandu
 
#include <Wire.h>   
#include <LiquidCrystal_I2C.h> 
 
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  
 
 
void setup()  
{
  lcd.begin(16,2);  
 
  lcd.backlight();  
  lcd.setCursor(0,0);
  lcd.print("Hello, world!");
  delay(500);
  lcd.setCursor(0,1); 
  lcd.print("BOTLAND.com.pl");
 
}
 
void loop() 
{
   lcd.backlight(); 
   delay(5000);
lcd.noBacklight(); 
   delay(5000);
}

Hi Erektuser

Can you post a link to details of the I2C converter you are using?

Do you know if it has pullup resistors already fitted to it for SDA and SCL? If not, you should add them yourself - 4k7 from SDA to Vcc and the same for SCL.

Regards

Ray

Hi Ray

Im using standard PCF8574 converter, datasheet is here https://botland.com.pl/index.php?controller=attachment&id_attachment=210

It has 4,7 k ? resistor attached, and it default address bus is 0x27 (according with a specifications on shop site)