$re = '/(?:\G|(?=\d+_.{16}E.*CON))(\d+)_(.*?)(EXE_CO|EXE_IN|CONTENT_ACCESS)/m';
$str = '1_11/08/2014 23:03EXE_IN1_11/08/2014 23:03EXE_CO2_12/08/2014 09:17CONTENT_ACCESS3_13/08/2014 09:17CONTENT_ACCESS
3_13/08/2014 09:17CONTENT_ACCESS1_11/08/2014 23:03EXE_IN2_11/08/2014 23:03EXE_CO
1_11/08/2014 23:03EXE_IN2_12/08/2014 09:17CONTENT_ACCESS3_13/08/2014 09:17CONTENT_ACCESS
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php