PHP serial communication - linux

Question

Hello, I made a php code for serial communication, this code worked in windows correctly, but I’m having problems with it in linux. To be able to communicate, I need to use the command -stty -F /dev/ttyS0 19200 -icanon. If I don’t use -icanon it doesn’t work. In doing so, I can only perform serial communication once, then it seems that Ubuntu is waiting for some feedback and I can’t read the data I need anymore. Follows my code:

$envio = fopen("/dev/ttyS0", "r+b");
fwrite($envio, "\x01\x04\x02\x3C\x00\x64\x30\x55");
$dadosHex = fread($envio, 75);
$run = substr($dadosHex, 113, 1);
fwrite($envio, "\x01\x04\x02\x3C\x00\x64\x30\x55");
$dadosHex1 = fread($envio, 75);
$run1 = substr($dadosHex1, 113, 1);
fclose($envio);

The $run variable returns the correct value, but $run1 does not return correctly. I realized that if I close and open the communication, both work, but I can’t do that because I need speed. Sorry any not formatting because I’m new around here.

Thank you very much.