A php-extension that provides parallel and optionally, serial-port/RS232 access to PHP for the Computer Aided Measuring Station (CAMS) project. Go to the CAMS repository to download or fork the php web-appplication codebase and related resources.

author: Lorenz Lo Sauer 2002; www.lsauer.com
website: https://github.com/lsauer/php-extension-cams-serialRS232
license: GPL license, Graphics: CC-BY-SA

description: As PHP 4.x does not provide hardware-port access through any library, a PHP extension was created. PHP allows easy extensibility through a dynamic link library/shared object (dll/so), when adhering to ZEND-interface specifications. Once compiled the dll/so is loaded dynamically at run time and can be accessed through the exported function names defined in the php_cams.h header-file:

ZEND_FUNCTION(cams_open);
ZEND_FUNCTION(cams_close);
ZEND_FUNCTION(cams_outp);
ZEND_FUNCTION(cams_inp);
ZEND_FUNCTION(cams_getport);

This flowchart shows the principal steps required for converting analog measurements to a digitally sampled signal via an n-bit Analog Digital Converter (ADC). The digital data is send to a parallel interface by mapping the opto-decoupled, parallel ADC output pins to the parallel port. The data is sampled and stored in a database, creating a time-series of sensor data, to be visualized on a PC.