Probleme on char to float conversion

[b707]

@adepressedstudent

char labviewSTR;

void loop() {
  if (Serial.available()>0)
  {
    labviewSTR = Serial.read();
    float labviewFLT = atof(labviewSTR);

Your labviewSTR variable is just a single character. And the atof function expects a char array.
In order to convert the data correctly, you must first read the entire string from the serial, not just the first character.

I think it would be better for you to read Serial Input Basics tutorial first