The web browsers (I know only those working in Windows) respect the single-domain restrictions. It means that they set special requirements for pages opened within domain A, trying to communicate with a domain B. As a consequence files stored on a local drive opened in a browser will not be able to read data from the web server of the PLC.
The solution is to use the CHROME browser and opening it with parameters "--disable-web-security --user-data-dir=ABC", where ABC will be the path to the direcotry in which the html file is stored. Do not worry, it will not switch off all you web security. Just the "same-origin policy" will be disabled. Here is the description of the parameter. It has been explained as: "Don't enforce the same-origin policy. (Used by people testing their sites.)"
Technically I propose to make a copy of the Chrome shortact a to modify it:
by adding at the end of the "Target" element the parameters: " --disable-web-security --user-data-dir=...".
For the change to take effect you need to close all instances of Chrome and reopen the browser. You should see the following message:
If you feel that for the normal everyday browsing you need Chrome without any modified parameters I propose to make a copy of the shortcut, modify it as described and rename it to, for example, "Chrome PLC".
After making the above changes html pages opened from the local drive should easily communicate with the PLC.
Other approaches are:
So, how to start? Donwload the Connection_Test.htm, change the ServerName variable value to your PLC's IP and:
If none of the above-mentioned options works - send an email - I will try to help.