Siemens SIMATIC S7-1200

Web server
12.7 User-defined Web pages
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
1055
12.7.2.11
Handling tag names that contain special characters
When specifying variable names in user-defined Web pages, you must take special care if
tag names contain characters that have special meanings.
Reading variables
You use the following syntax to read a variable (Page 1044):
:=<Varname>:
The following rules apply to reading variables:
● For variable names from the PLC tag table, enclose the tag name in double quotation
marks.
● For variable names that are data block tags, enclose the data block name in double
quotation marks. The tag is outside of the quotation marks.
● For variable names that are direct I/O addresses, memory addresses, or alias names, do
not use quotation marks around the read variable.
● For tag names or data block tag names that contain a backslash, precede the backslash
with another backslash.
● If a tag name or data block tag name contains a colon, less than sign, greater than sign,
or ampersand define an alias that has no special characters for the read variable, and
read the variable using the alias. Precede colons in tag names in a Use clause with a
backslash.
Table 12- 1 Examples of Read variables
Data block name
Tag name
Read command
n/a ABC:DEF
<!--AWP_Out_Variable Name='special_tag'
Use ='"ABC:DEF"' -->
:=special_tag:
n/a
T\
:="T\\":
n/a A \B 'C :D
<!--AWP_Out_Variable
Name='another_special_tag' Use='"A \\B \'C
:D"' -->
:=another_special_tag:
n/a a<b
<!--AWP_Out_Variable Name='a_less_than_b'
Use='"a<b"' -->
:=a_less_than_b:
Data_block_1
Tag_1
:="Data_block_1".Tag_1:
Data_block_1 ABC:DEF
<!-- AWP_Out_Variable Name='special_tag'
Use='"Data_block_1".ABC\:DEF'-->
:=special_tag:
DB A' B C D$ E
Tag
:="DB A' B C D$ E".Tag:
DB:DB Tag:Tag
<!--AWP_Out_Variable Name='my_tag' Use
='"DB:DB".Tag\:Tag' -->
:=my_tag: