Special Tags - Siemens SIMATIC S7-1500 Function Manual

3.16.1.2

Special tags

Special tags
The special tags are mainly the so-called HTTP tags that are defined in the definitions of the
World Wide Web Consortium (W3C). Special tags are also used for cookies and server tags.
Reading special tags
The web server can read PLC tags and pass them to special tags in the HTTP response
header. You can, for example, read out a path name from a PLC tag to redirect the URL to
another storage location with the special tag "HEADER:Storage location".
Syntax
<!-- AWP_Out_Varible Name='<Type>:<Name>' Use='<Varname>' -->
<Type> corresponds to the type of the special tag.
Options are:
● HEADER
● COOKIE_VALUE
● COOKIE_EXPIRES
<Name> corresponds to the name of the HEADER tag or the cookie:
● HEADER tags:
– Status: HTTP status code (if no other value is set, status code 302 is returned).
– Location: Path for redirection to another page. Status code 302 must be set.
– Retry-After: Time for which the service is most likely not available. Status code 503
● COOKIE_VALUE:name: Value of the named cookies.
● COOKIE_EXPIRES:name: Delay time of the named cookie in seconds.
Examples
The HTTP HEADER tag is written to the PLC tag of the same name:
<!-- AWP_Out_Variable Name='"HEADER:Status"' -->
If the name of the special tag is not identical with the name of the PLC tag, you can assign it
to a PLC tag with the "Use" parameter:
<!-- AWP_Out_Variable Name='"HEADER:Status"' Use='"Status"' -->
Web server
Function Manual, 11/2019, A5E03484625-AG
must be set.
Web pages
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