PHP Socket - send binary data - php

Question

How to send binary data representing 01 (PHP)?
My Server code (sockets TCP, address is only example. I use my server address of course)
error_reporting(E_ALL);
set_time_limit(0);
ignore_user_abort(true);
$address = '11.111.111.111'; // example server address
$port = 9000; // example port
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1);
socket_bind($sock, $address, $port);
socket_listen($sock);
$clients = array($sock);
while(true) {
$read = $clients;
if (socket_select($read, $write = NULL, $except = NULL, 0) < 1) {
continue;
}
if (in_array($sock, $read)) {
$clients[] = $newsock = socket_accept($sock);
$key = array_search($sock, $read);
unset($read[$key]);
}
foreach ($read as $read_sock) {
$data = #socket_read($read_sock, 1024);
if ($data === false) {
// remove client for $clients array
$key = array_search($read_sock, $clients);
unset($clients[$key]);
echo "client disconnected.\n";
// continue to the next client to read from, if any
continue;
}
$data = trim($data);
// check if there is any data after trimming off the spaces
if (!empty($data)) {
// send this to all the clients in the $clients array (except the first one, which is a listening socket)
foreach ($clients as $send_sock) {
// if its the listening sock or the client that we got the message from, go to the next one in the list
if ($send_sock == $sock || $send_sock == $read_sock) {
continue;
}
$fp = fopen('socket_communication.txt', 'a');
fwrite($fp, date("Y-m-d H:i:s")." - DATA ".$data."\n");
fclose($fp);
$value = unpack('H*', "1");
$response = base_convert($value[1], 16, 2);
socket_write($send_sock, $response, 1);
} // end of broadcast foreach
}
}
}
echo "Closing sockets...";
socket_close($sock);
I would like to server sent binary data (01 or 1).
I use unpack function and convert it by base_convert but it doesnt works.
This code send response to client
$value = unpack('H*', "1");
$response = base_convert($value[1], 16, 2);
socket_write($send_sock, $response, 1);