HX3 determines whether EEPROM is 8-bit word addressed or 16-bit word addressed using I2C slave address. It first attempts to read on slave address 0x50 (7-bit addressing) and proceeds if there is an ack for this slave address. If NACK, then it proceeds to read on slave address 0x51.
All small sized EEPROMs such as 24LC02B does not use A0 pin and slave address is 0x50. All large EEPROMs has A0 pin and should be pulled high to make the slave address as 0x51.
Please pull A0 pin high on your EEPROM to make the slave address as 0x51 and then HX3 would use 16-bit word address.
So it's fixed 0x51 (7-bit addressing) for 16bit word address.
For Eeprom GT24P128C has only 4 Pins, haven't A0 PIN. I should change to GT24P128CA2.