src/Server/Asyn/MQTT/Utility.php
static public function ASCII2Visible($char, $replace='.')
    {
        $c = ord($char);
        if ($c >= 0x20 && $c <= 0x7F) {
            return $char;
        } else {
            return $replace;
        }
    }
static public function ASCII2Visible($char, $replace='.')
    {
        $c = ord($char);
        if ($c >= 0x20 && $c <= 0x7F) {
            return $char;
        } else {
            return $replace;
        }
    }
static public function ASCII2Visible ( $ char , $ replace = '.' ) { $ c = ord ( $ char ) ; if ( $ c >= 0x20 && $ c <= 0x7F ) { return $ char ; } else { return $ replace ; } }
Convert ASCII Invisible Character to Visible

@param string $char
@param string $replace   Default Control Character to '.'
@return string
Convert ASCII Invisible Character to Visible