Constraints - Siemens S7-1200 System Manual

Web server

11.7 Constraints

11.7 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 665). 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 613), you can download and import the certificate
into the Internet options of your Web browser (Page 666). 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 HTTP 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 connection.
If, for example, you are using Mozilla Firefox 8, which supports 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.
Note
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.
664
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG