Special Tags - Siemens SIMATIC S7-1500 Function Manual

Websites
3.8 User pages
3.8.1.2

Special tags

Special tags
Special tags are mainly the HTTP tags specified 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 transfer 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 special tag.
Options are:
● HEADER
● COOKIE_VALUE
● COOKIE_EXPIRES
<Name> corresponds to the name of the HEADER tag or the cookie:
● HEADER tags:
● COOKIE_VALUE:name: value of the named cookie.
● COOKIE_EXPIRES:name: expiration 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"' -->
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– Status: HTTP status code (if no other value was set, status code 302 is returned).
– Location: path for redirection to another site. Status code 302 must be set.
– Retry-After: time for which the service is most likely not available. Status code 503
must be set.
Function Manual, 01/2013, A5E03484625-01
Web server