Rockwell Automation Logix 5000 User Manual

Chapter 1 Program a Function Block Diagram
Rockwell Automation Publication 1756-PM009J-EN-P - March 2022 13
For a:
Specify:
Tag
tag_name
Bit number of a larger data type
tag_name.bit_number
Member of a structure
tag_name.member_name
Element of a one dimension array
tag_name[x]
Element of a two dimension array
tag_name[x,y]
Element of a three dimension array
tag_name[x,y,z]
Element of an array within a structure
tag_name.member_name[x]
Member of an element of an array
tag_name[x,y,z].member_name
where:
x is the location of the element in the first dimension.
y is the location of the element in the second dimension.
z is the location of the element in the third dimension.
For a structure within a structure, add an additional member_name.
Define execution order (flow of data) by wiring elements together and
indicating any input (feedback) wires, if necessary. The location of a block
does not affect the order in which the blocks execute.
When an IREF specifies input data for a function block instruction, the data
in that IREF is latched for the scan of the function block routine. The IREF
latches data from program-scoped and controller-scoped tags. The controller
updates all IREF data at the beginning of each scan as shown in this diagram.
In this example, the value of tagA is stored at the beginning of the execution
of the routine. The stored value is used when Block_01 executes. The same
stored value is also used when Block_02 executes. If the value of tagA changes
Define the order of
execution
Data latching

Rockwell Automation Logix 5000 Specifications

General

Brand	Rockwell Automation
Model	Logix 5000
Category	Controller
Language	English