CIP Services and User-created Tags
Rockwell Automation Publication 1756-PM020F-EN-P - January 2019 51
• The Symbol Name contains leading double underscores (for
example, __ABC) (eliminates some system tags)
• The Symbol Name contains a colon (:) (for example, eliminates
Module-Defined tags)
3. For the structure tags that remain (bit 15=1), access the Templates and
discard tags where the Template Name, or the name of the first
member of the structure, contains leading double underscores or a
colon (:) This eliminates Add-On-Defined tags and aliases of
Module-Defined tags.
For template details, see Step 3: Determining the structure makeup for
a specific structure.
4. Locate any nested member structures within the remaining structures,
by checking the Type of each member. For any nested structures,
repeat the checks earlier for Type in valid range, Template Name and
first Member Name, and discard the total structure if a check fails.
Continue until all nested structures are checked.
See also
Step 3: Determining the structure makeup for a specific structure
on
page 51
Any remaining tag with the Symbol Type Bit 15 = 1 is a structured data type.
The client application must read information from the Template object
Instance ID associated with this tag. This Instance ID is the value of Symbol
Type, Bits 0-11. Four attributes of this instance contain information about
structured data types for a client application that interacts with a UDT-based
tag.
Read these Template Instance attributes, using the instance ID in the Request
Path of the Get_Attribute_List service (0x03) to the Template class (0x6C).
Attribute Description/Characteristics
1
This is the Tag Type Parameter used in Read/Write Tag service
• Structure Handle
• Data Type: UINT
2
This is the number of structure members
• Template Member Count
• Data Type: UINT
4
• This is the number of 32-bit words
• Template Object Definition Size
• Data Type: UDINT
5
This is the number of bytes of the structure data
• Template Structure Size
• Data Type: UDINT
structure makeup for a
specific structure
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