Allen-Bradley 1756-L65 ControlLogix 5565, Programming Manual

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Rockwell Automation Publication 1756-PM004D-EN-P - September 2012 47
Organizing Tags Chapter 2
Address Tag Data A tag name follows this format.
Name [Element] .Member [Element] .Bit
or
.[Index]
= Optional
Where Is
Name Name that identifies this specific tag.
Element Subscript or subscripts that point to a specific element within an array.
· Use the element identifier only if the tag or member is an array.
· Use one subscript for each dimension of the array. For example: [5], [2,8], [3,2,7].
To indirectly (dynamically) reference an element, use a tag or numeric expression that provides the element number.
· A numeric expression uses a combination of tags, constants, operators, and functions to calculate a value. For example, Tag_1-Tag_2,
Tag_3+4, ABS (Tag_4).
· Keep the value of the tag or numeric expression within the dimensions of the array. For example, if a dimension of an array contains 10
elements, then the value of the tag or numeric expression must be
0…9 (10 elements).
Member Specific member of a structure.
· Use the member identifier only if the tag is a structure.
· If the structure contains another structure as one of its members, use additional levels of the . Member format to identify the required
member.
Bit Specific bit of an integer data type (SINT, INT, or DINT).
Index To indirectly (dynamically) reference a bit of an integer, use a tag or numeric expression that provides the bit number.
· A numeric expression uses a combination of tags, constants, operators, and functions to calculate a value. For example, Tag_1-Tag_2,
Tag_3+4, ABS(Tag_4).
· Keep the value of the tag or numeric expression within the range of bits of the integer tag. For example, if the integer tag is a Dint (32-bits),
then the value of the index must be 0…31 (32-bits).