EDIT: I have done some testing with the following script (found here: PHP serial port data return from Arduino). Hp Laserjet 1015 Driver Windows 7 64 Bit. It appears that even using fwrite to /dev/ttyUSB0 outputs my new command plus the last.

I have installed xampp in fedora 13.I am trying to communicate with microcontroller through serial port using php serial class. My code is example.php include('php_serial.class.php'); $serial = new phpSerial(); $serial->deviceSet('0'); $serial->confBaudRate(9600); //Baud rate: 9600 $serial->confParity('none'); //Parity (this is the 'N' in '8-N-1') $serial->confCharacterLength(8); //Character length (this is the '8' in '8-N-1') $serial->confStopBits(1); //Stop bits (this is the '1' in '8-N-1') $serial->confFlowControl('none'); //Device does not support flow control of any kind, so set it to none. //Now we 'open' the serial port so we can write to it $serial->deviceOpen(); $serial->sendMessage('*1' ); //sleep(1); // echo 'hi'; $serial->deviceClose();?>Hp 9420 Drivers Windows 7. The php script gets executed but gives the following warnings. Warning: Specified serial port is not valid in /opt/lampp/htdocs/xampp/php_serial.class.php on line 147 Warning: Unable to set the baud rate: the device is either not set or opened in /opt/lampp/htdocs/xampp/php_serial.class.php on line 241 Warning: Unable to set parity: the device is either not set or opened in /opt/lampp/htdocs/xampp/php_serial.class.php on line 295. I have used the command: chmod 0777 /dev/ttyUSB0 to give permissions.