String txtParams = Serial.readString();

    int _1stSeparator = txtParams.indexOf(',');
    int _2ndSeparator = txtParams.indexOf(',', _1stSeparator + 1);
    int _3ndSeparator = txtParams.indexOf(',', _2ndSeparator + 1);
    int _4ndSeparator = txtParams.indexOf(',', _3ndSeparator + 1);

    String firstParams  = txtParams.substring(0, _1stSeparator);
    String secondParams = txtParams.substring(_1stSeparator + 1, _2ndSeparator);
    String thirdParams  = txtParams.substring(_2ndSeparator + 1, _3ndSeparator);
    String fourthParams = txtParams.substring(_3ndSeparator + 1, _4ndSeparator);