public function convert_csv($csv, $json)
{
    /*
     * Open files.
     */
    $csv_handle = fopen($csv, 'r');
    $json_handle = fopen($json, "w");
    /*
     * Get the table headers.
     */
    $headers = fgetcsv($csv_handle);
    /*
     * Write the array name.
     */
    fwrite($json_handle, ""LogData":[");

    $FirstRecord = true;
    while ($row = fgetcsv($csv_handle))
    {
        /*
         * Ensure no trailing comma after last record.
         */
        if (!$FirstRecord)
            fwrite($json_handle, ",");
        else
            $FirstRecord = false;
        /*
         * Create JSON record and write to file.
         */
        $complete = array_combine($headers, $row);
        fwrite($json_handle, json_encode($complete));
    }
    /*
     * Close the array
     */
    fwrite($json_handle, "]");
    /*
     * Close the files.
     */
    fclose($csv_handle);
    fclose($json_handle);
}

TimeStamp,Value
1390364805600.01,2.0
1390451205600.01,3.0
1390537605600.01,0.5
1390546245600.02,23.0
1390563525599.99,0.8

"LogData":[{"TimeStamp":"1390364805600.01","Value":"2.0"},{"TimeStamp":"1390451205600.01","Value":"3.0"},{"TimeStamp":"1390537605600.01","Value":"0.5"},{"TimeStamp":"1390546245600.02","Value":"23.0"},{"TimeStamp":"1390563525599.99","Value":"0.8"}]

$this->logging_model->convert_csv($path, "/tmp/log.json");
//header('Content-Type: application/json');  // I have tried with and without this line
readfile("/tmp/log.json"); // push it out

$.ajax({
    url: URL,
    type: "GET",
    dataType: "json",
    success: function(data) { SaveData(PointId, data);},
    error: function (request, status, error) { alert(error);},
    async: false
});