Hello,

If you noticed, the webserver interface of S7-1200 is pretty fast, but when it comes to your web app (over 100K) its takes a while, almost 3-5 seconds.

After some snooping, I saw that the webserver interface responds with 304 (Not Modified) to non dynamic files (images, css, js....). It also adds Etag header as a cache mechanism.

I would also like to do that with my web app, but I can't find any documentation regarding this cache setup. I don't think is it possible, but maybe someone has an idea how to setup cache control in a webapp.

Thank you,
Alex

This is because the webserver does not set the "Cache-Control" header of HTTP responses. There is no way to configure this. This would make every request of user defined pages at least 2-5 seconds faster if you have some .js and .css files that never change.

If this may suit your needs there is a workaround to install a brower addon and inject the cache header yourself. The addon is called Requestly. And you set the response header of that particular domain (the ip of your PLC) 'Cache-Control' to 'max-age=3600' for example.

Siemens please fix.

Hey 

You can prevent that behavior by using asynchronous methods --> AJAX

just have a look into the extended examples for Web server and the JSON, AJAX and POST features.

https://support.industry.siemens.com/cs/de/en/view/68011496

That may help to get a better response time while using the S7 Web-server.
You / Your Web browser just need to load the whole application once, and afterwards you just need to reload and update the changed actual values from the PLC and deploy them via JavaScript into your Webapplication.

Hope that helps to reduce the actualisation time of your app. :-)