Splitting a float into bytes for storage in FRAM (like EEPROM)
I solved it with the use of UNION:

//---------------------------------------------------------
union Scomp_float {
  // si utilizza union x float
  float temp;
  char byte_s[4];
} S_float;

//---------------------------------------------------------
//-------------------------FLOAT--------------------------------
float mioFlo = 123456.29;  
byte f0 = 0;  // contengono i byte del float
byte f1 = 0;
byte f2 = 0;
byte f3 = 0;
S_float.temp = mioFlo;
f0 = S_float.byte_s[0];
f1 = S_float.byte_s[1];
f2 = S_float.byte_s[2];
f3 = S_float.byte_s[3];
Serial.println(f0);
Serial.println(f1);
Serial.println(f2);
Serial.println(f3);
fram.writeEnable(true);
fram.write8(7, f0);
fram.writeEnable(false);
fram.writeEnable(true);
fram.write8(8, f1);
fram.writeEnable(false);
fram.writeEnable(true);
fram.write8(9, f2);
fram.writeEnable(false);
fram.writeEnable(true);
fram.write8(10, f3);
fram.writeEnable(false);
S_float.byte_s[0] = fram.read8(7); // si ricompone il float
S_float.byte_s[1] = fram.read8(8);
S_float.byte_s[2] = fram.read8(9);
S_float.byte_s[3] = fram.read8(10);
float masterFloat = S_float.temp;
Serial.println(masterFloat);
//-------------------------FLOAT--------------------------------