Web server

Modern automation technology increasingly integrates internet technologies with Ethernet-based PLCs , for example, direct access to the PLC system via the intranet. During the test and commissioning phase, the commissioning engineer wants to have flexible access to the CPU; individual data are to be visualized during operation for diagnostic purposes: For access mechanisms via the internet or intranet it is reasonable to use already existing standards such as the http technology, standard web browsers and common “languages” such as HTML or JavaScript. SIMATIC CPUs with PROFINET interface provide the opportunity to access variables of the CPU with the help of web pages provided by the system. The integrated web server of the S7-CPU is accessed via a standard web browser. In addition to the standard mechanisms of the web page such as identification, diagnostic buffer, module status, communication, variable status and data log, individual web pages can be designed and called for your particular application. The Web server provides Web page access to data about your CPU and to the process data within the CPU. With these Web pages, you access the CPU with the Web browser of your PC or mobile device.

The standard web pages allow authorized users to perform a variety of functions:

  • ● You can change the operating mode (STOP and RUN) of the CPU.
  • ● You can monitor and modify the status of the PLC tags.
  • ● You can view and download any data logs being collected by the CPU.
  • ● You can view the diagnostic buffer of the CPU

The process involves following steps:

  1. 1.      Create the HTML pages with an HTML editor, such as Microsoft Frontpage
  2. 2.      Include AWP commands in the HTML code: The AWP commands are a fixed set of commands for         accessing CPU Information.
  3. 3.      Configure STEP 7 to read and process the HTML pages.
  4. 4.      Generate the program blocks from the HTML pages.
  5. 5.      Program STEP 7 to control the use of the HTML pages.
  6. 6.      Compile and download the program blocks to the CPU.
  7. 7.      Access the user-defined Web pages from your PC or mobile device.