Entry type: FAQ, Entry ID: 21975526, Entry date: 12/18/2015
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Why is it not possible to establish a connection to the web server of the WinCC flexible or WinCC (TIA Portal) Runtime?

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Under certain circumstances with a web browser it is not possible to establish a connection to the web server of the WinCC Runtime Advanced or WinCC flexible Runtime. One reason for this might be a conflict in the assignment of the IP ports.

If it is not possible to access the web server of a computer with WinCC Runtime Advanced or WinCC flexible Runtime from an external computer, one possible cause might be a conflict with the port assignment on the server PC: by default the WinCC web server uses the port "80" for HTTP communication. If another service is using the same port on the server PC, this results in an access conflict.

Symptoms
When attempting to access the web pages of the Runtime, the web browser of the client PC responds with the message "...under construction", "Error 404" or "The page cannot be found". (Exactly how the error message looks depends on the browser used and its version.)

Remedy
WinCC flexible and WinCC (TIA Portal) have an automatic mechanism to solve these conflicts.

  • WinCC flexible: WinCC flexible 2008 SP1 Upd 4 and higher
  • WinCC (TIA Portal): V13 and higher

WinCC checks whether Port 80 is already occupied. If this is the case, successively higher port numbers (81, 82, ...) are tested until a free port is found. In this case you must instruct the browser of the client to use the new port as well.
   
  1. On the server computer you open the Windows Task Manager and go to the "Processes" tab. Enable the "Show processes of all users" option.
       
  2. If no process IDs are displayed in the process table, have them shown by going to the main menu and selecting the item "View -> Select columns..." and in the dialog that opens you mark the item "PID (Process ID)".
       
  3. In the table you search "MiniWeb.exe" under Image Name. Note the associated process ID (here: "3140").
       

    Fig. 01
       
  4. Open the input prompt by entering the "cmd" command in the Start menu. Then call "netstat -ano" with the command line. This tool, included in the Windows delivery package, lists all the processes running on the computer along with their process IDs.
       
  5. Search in the last column ("PID") for an item with the process ID of the MiniWeb. In the second column of that item ("Local Address") is the IP address and the port via which MiniWeb communicates separated by a colon ":". (Here: IP address "172.16.33.4", Port "81")
       

    Fig. 02
     
     
Instruct your browser on the client to use the port you found by adding a colon and the port to the IP address in address field, in this example "172.16.33.4:81" instead of "172.16.33.4".

Now you can access the web pages.

Alternative resolution of conflict
If you do not want to change the port, instead you can delete or reconfigure the other application that is using the port.
Possible origins of the conflicts described:

"Internet Information Services (IIS)"
This is an extendable web server offered by Microsoft Windows as an optional component. Disable the IIS if a port conflict arises and you do not necessarily need these services.
For this, in Windows 7 you go to the Control Panel and open "Programs and Features" (in Windows XP: "Software"). Select "Turn Windows features on or off" (Windows XP: "Add/Remove Windows Components") to get a list of the available Windows components. Clear the check box for the "Internet Information Services" feature. (You need administrator rights for this.)
   


Fig. 03
   

"IPC DiagMonitor"
IPCs are supplied with the diagnostics tool "IPC DiagMonitor" that communicates via Port 80 like the web server.
Change the configuration of the "IPC DiagMonitor" so that Port 80 is no longer used.
To do this you go to the Start menu and open the item "Siemens Automation -> DiagMonitor -> WebServer -> Configuration". The XML file with the configuration parameters opens in a text editor. Find the code "PORTNUMBER VALUE" and change its value to "5009".
  


Fig. 04

Then save the modified file.

Additional Keywords
HTML pages, HTML, Web service SmartAccess