Webvisu not supported due to missing browser feature HTML5-Canvas

2019-01-28
2019-02-01
  • Tim.Manning

    Tim.Manning - 2019-01-28

    I am starting to use Codesys Visualization, and I am testing a simple display using Webvisu, using the Soft-PLC. I have the Device configured as a 'CODESYS Control Win V3' device.

    The Soft-PLC is running on a PC running Windows 10 Pro, and I am using Codesys version 3.5.12

    I have tested this using Chrome 71.0.3578.98 (64-bit) on the same machine as the Soft-PLC.

    I have also tested this using Chrome 71.0.3578.98 (64-bit) and Internet Explorer 11.523.17134.0 on a remote PC, connecting to the PC running the Soft-PLC remotely.

    The first time I downloaded the application to the Soft PLC and connected with the browser (localhost:8080/webvisu_arraytest.htm or xxx.xxx.xxx.xxx:8080/webvisu_arraytest.htm), things were working. The buttons worked and the live data was updating.

    However, after a minute or so, things stopped working:

    1. Sometimes some of the elements do not get displayed - they are invisible on the screen. However, if I hover the cursor over where they are supposed to be, the cursor changes to a pointer

    2. The buttons on the screen, when they are displayed, appear to be active. However, except during the first few minutes, they no longer work.

    3. The live data stopped updating on the screen after the first few minutes.

    I have rebooted my PC and redownloaded the application to the Soft PLC, and nothing seems to be working to correct this.

    From Chrome, if I select 'Inspect' from the web page, I see the message 'Webvisu not supported due to missing browser feature HTML5-Canvas'

    From IE, if I select view source, I see the message 'Webvisu not supported due to missing browser feature HTML5-Canvas'.

    After searching on the Internet for a while, it is my understanding that both of these browsers support HTML5-Canvas.

    Do I need to somehow enable the HTML5-Canvas feature on the browser? I couldn't find anything on the Internet about that. Is thers something else I am doing wrong? Or, is this some other bug?

     
  • m.prestel

    m.prestel - 2019-01-29

    Hello Tim,

    in regards of 'Webvisu not supported due to missing browser feature HTML5-Canvas':
    What you see is the fallback message, if no canvas (HTML-Tag ) is supported by your browser.
    Since you however can see some buttons and don't see this message directly, you are good there.

    "However, after a minute or so, things stopped working:" -> Could you maybe check if the runtime is reporting any issue like "Event Buffer full. Dropping event"

    If this is not the case, could you maybe provide the example application?

    Best regards,
    Marcel

     
  • Tim.Manning

    Tim.Manning - 2019-01-29

    Marcel,

    Yesterday, I was doing some stress testing (project Vis_Test_Simulator_20190129). I have a page where I have three frames, and each frame can display one of 4 arrays ( ARRAY of [1..10,1..100] OF BYTE (or WORD, or DWORD or LWORD)).

    After I read your reply, I created a similar project, but in this case I the pages have three arrays of only 100 elements (ARRAY 1..10, 1..10 OF dutVisu). This project seems to work OK, so I am assuming I am hitting some kind of limit somewhere in my other project. However, I didn't see any runtime messages - the only thing I saw was the message about Canvas, and I only found that by inspecting the web page.

    I am attaching two project archives.

    Vis_Test_Simulator_20190129 - the opening page is webvisu_arraytest.htm - This one is the one that doesn't work.
    Simple_WebVisu - the opening page is webvisu.htm - This is the one that does work.

     
  • Tim.Manning

    Tim.Manning - 2019-01-29

    Marcel,

    For some reason, I am not able to upload files to the forum. Is there another way to get the files to you?

     
  • m.prestel

    m.prestel - 2019-01-31

    Hello Tim,

    please send it to me via the store using the "My question" feature.

    Best regards,
    Marcel

     
  • Tim.Manning

    Tim.Manning - 2019-01-31

    Marcel,

    I am sending these files now. I am sure that I am hitting some kind of limit, so now my questions are:

    1. Are there any published specifications describing the limits of what can be put on a Webvisu visualization?

    2. Is there any functionality that is not supported in Webvisu, but is supported in the other visualizations?

    Thanks,

    Tim

     
  • m.prestel

    m.prestel - 2019-02-01

    Hello Tim,

    thank you for your project!
    Looks like you simple found a bug in the SP12 branch, which is already fixed using a SP13 visu profile.

    In regards your two questions:
    1: In short, no there are not really any known limitations, at least not known for me.
    There are some technical limits, like having a lot of strings using different fonts, but that is all caused by the browser recalculating all the styles.

    2: I only know the limitation that ActiveX-Controls cannot be used in the browser due to browser not widely supporting them.

    Best regards,
    Marcel

     
  • Tim.Manning

    Tim.Manning - 2019-02-01

    Marcel,

    Thanks for the update. Since I am using the Bedrock implementation of Codesys, we are a couple of Service packs back. I'll note this and move on, with the expectation that I'll get this fix soon.

    Tim

     

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