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Siemens AG
Entry type: FAQ Entry ID: 109763463, Entry date: 04/07/2021

Why are user-defined web pages not displayed completely when called via the VPN connection of a LOGO! CMR20x0?

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When the user-defined web page of the LOGO! BM is called via the VPN connection of the LOGO! CMR the display might be restricted in the browser, which in turn restricts the user-defined web page. In this FAQ response we consider the cause of this and the possible solutions.

The FAQ response requires the following:

  • VPN connection to the LOGO! CMR20x0 is established.
  • LOGO! BM is accessible via the OpenVPN tunnel of the LOGO! CMR20x0.
  • LOGO! BM web server with created, user-defined web page is enabled.

Information about this is available in the following entries:
"Setting up a Secure VPN Connection between a PC and LOGO! 8" 
"LOGO! Web Based Trainings" 

General Information
If you use user-defined web pages via the LOGO! CMR, then you have to take the following points into account:

  • The download speed of the system files depends, in addition to the cellular radio standard (GPRS, UMTS, LTE), also on the quality of the mobile telephone network and other factors.

  • The first time that the user-defined web page is set up, diverse files and scripts have to be downloaded. With LOGO! 8 FS:04 and higher there is a timeout for each single file. This timeout can prevent all the necessary files being downloaded via the VPN connection of the LOGO! CMR.

  • Files are stored in the cache of the browser for repeated access in order to prevent reloading for each new access. This greatly reduces the repeated downloading time above all via VPN.

If you use user-defined web pages via the LOGO! CMR, then the following might occur:

  • The system files could not be downloaded completely.
    No data can be displayed without these system files. The web page is unusable.

Fig. 1

  • An image file (a background image, for example) could not be downloaded.
    An image file might exceed a critical size. This file is downloaded after the system files. If the background cannot be downloaded, only the graphics are not displayed. The user-defined web page can be used.

The following points help you to clear display problems of the user-defined web pages via the LOGO! CMR:

  • The system files / background images must be located in the cache of the browser being used. Enable the cache function of your browser. Then use your browser to download the user-defined web pages locally via the LAN connection of the LOGO! BM.

  • The size images can be reduced by saving them in other file formats or in a lower image quality. Here you should primarily aim for the "golden mean" between quality and compression. The formats ".jpg", ".png" and ".gif" are recommended.

  • If you change the user-defined web page you can download large files locally. As long as the system files are successfully downloaded the web page is displayed without new images.     

This FAQ response is valid for the following modules:

  • LOGO! 8 as of FS:04 ... LOGO! BM <8.3
  • LOGO! CMR2020 (6GK7142-7BX00-0AX0) with firmware <V2.1.8
  • LOGO! CMR2040 (6GK7142-7EX00-0AX0) with firmware <V2.1.8
  • LOGO! Web Editor (LWE <V1.1)

As of LOGO! BM 8.3 and LWE V1.1, you can access user-defined web pages of the LOGO! BM via the LOGO! CMR2020 and CMR2040 without restrictions.

Further Information
Detailed information about firmware 2.1.8 for CMR2020 and CMR2040 is available in the entry 109792919.

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit
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