src/PhpSerial.php
public function sendMessage($str, $waitForReply = 0.1)
    {
        $this->_buffer .= $str;

        if ($this->autoFlush === true) {
            $this->serialflush();
        }

        usleep((int) ($waitForReply * 1000000));
    }
public function sendMessage($str, $waitForReply = 0.1)
    {
        $this->_buffer .= $str;

        if ($this->autoFlush === true) {
            $this->serialflush();
        }

        usleep((int) ($waitForReply * 1000000));
    }
Sends a string to the device

@param string $str          string to be sent to the device
@param float  $waitForReply time to wait for the reply (in seconds)