Constraints - Siemens SIMATIC S7-1200 System Manual

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12.8 Constraints

The following IT considerations can affect your use of the Web server:

● Typically, you must use the IP address of the CPU to access the standard Web pages or

user-defined Web pages, or the IP address of a wireless router with a port number. If

your Web browser does not allow connecting directly to an IP address, see your IT

administrator. If your local policies support DNS, you can connect to the IP address

through a DNS entry to that address.

● Firewalls, proxy settings, and other site-specific restrictions can also restrict access to the

CPU. See your IT administrator to resolve these issues.

● The standard Web pages use JavaScript and cookies. If your Web browser settings

disable JavaScript or cookies, enable them. If you cannot enable them, some features

are restricted (Page 1083). Use of JavaScript and cookies in user-defined Web pages is

optional. If used, you must enable them in your browser.

● The Web server supports Secure Sockets Layer (SSL). You can access the standard

Web pages and user-defined Web pages with an URL of either http://ww.xx.yy.zz or

https://ww.xx.yy.zz, where "ww.xx.yy.zz" represents the IP address of the CPU.

● Siemens provides a security certificate for secure access to the Web server. From the

Introduction standard Web page (Page 1017), you can download and import the

certificate into the Internet options of your Web browser (Page 1085). If you choose to not

import the certificate, you will get a security verification prompt every time you access the

Web server with https://.

Number of connections

The Web server supports a maximum of 30 active connections. Various actions consume the

30 connections, depending on the Web browser that you use and the number of different

objects per page (.css files, images, additional .html files). Some connections persist while

the Web server is displaying a page; other connections do not persist after the initial

If, for example, you are using certain versions of Mozilla Firefox, which support a maximum

of six persistent connections, you could use five browser or browser tab instances before the

Web server starts dropping connections. In the case where a page is not using all six

connections, you could have additional browser or browser tab instances.

Also be aware that the number of active connections can affect page performance.

Log off prior to closing Web server

If you have logged in to the Web server, be sure to log off prior to closing your Web browser.

The Web server supports a maximum of seven concurrent logins.

S7-1200 Programmable controller

System Manual, V4.2, 09/2016, A5E02486680-AK