reciving binary data in http POST

i have a device (time attendance) that send POST data to my server every 10 seconds. ( i cant control or change the way it send data) so in my server in php file i run print_r($_POST) and it is empty, i can see the data only when i run this $content = file_get_contents('php://input'); var_dump($content); //or i can use print_r($content); i save those to a file and result are some json and BINARY DATA (CHECK atachment) but in php i cant get the binary , coz i see strange characters, few developer tried and they were not able to get it in php so is there a way to get that binary and convert to ascii or whatever u like and then save to a file or send to php or whatever, so i just want to recive binary and decode so i can see what info is there p.s HTTP request Content-type is: [Content-Type] => application/octet-stream, application/octet-stream