Common Attributes for Advanced Process Control and Drives Instructions
540 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Important:
The math status flags are set based on the stored value. Instructions that normally do not affect
math status flags might appear to affect math status flags if type conversion occurs from mixed
data types for the instruction parameters. The type conversion process sets the math status
flags.
Expressions in Array Subscripts
Controllers Description
CompactLogix 5380,
CompactLogix 5480,
ControlLogix 5580,
Compact GuardLogix
5380, and GuardLogix
5580 controllers
Expressions do not set status flags based on the results of math operations. If expressions
overflow:
• A minor fault generates if the controller is configured to generate minor faults.
• A major fault (type 4, code 20) generates because the resulting value is out of range.
CompactLogix 5370,
ControlLogix 5570,
Compact GuardLogix
5370, and GuardLogix
5570 controllers
Expressions set status flags based on the results of math operations. If an array subscript is an
expression, the expression and the instruction could generate minor faults.
Tip:
If an array subscript is too large (out of range), a major fault (type 4, code 20) generates.
When you enter an immediate value (constant) in decimal format (for example, -
2, 3) the controller stores the value by using 32 bits. If you enter a value in a radix
other than decimal, such as binary or hexadecimal, and do not specify all 32 bits,
the controller places a zero in the bits that you do not specify (zero-fill).
Important:
Zero-fill of immediate binary, octal or hexadecimal values less than 32
bits.
If you enter The controller stores
-1 16#ffff ffff (-1)
16#ffff (-1) 16#0000 ffff (65535)
8#1234 (668) 16#0000 029c (668)
2#1010 (10) 16#0000 000a (10)
Integer Immediate Values
If you enter The controller stores
Without any suffix DINT
"U" UDINT
"L" LINT
"UL" ULINT
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