Common Attributes for Advanced Process Control and Drives Instructions
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018 541
Floating Point Immediate Values
If you enter The controller stores
Without any suffix REAL
"L" LREAL
Data conversions occur when mixing data types in programming.
When programming: Conversions can occur when you:
Ladder Diagram
Structured Text
Mix data types for the parameters within one
Instruction or expression.
Function Block Wire two parameters that have different data types
Instructions execute faster and require less memory if all the operands of the
instruction use:
• The same data type.
• An intermediate data type:
• All function block instructions support one data type operand only.
• If mixing data types or use tags that are not the optimal data type, the
controller converts the data according to these rules:
• Operands are converted according to the ranking of data types
from SINT, USINT, INT, UINT, DINT, UDINT, LINT,
ULINT, REAL, and LREAL with ranking from 1 (the lowest) to
10 (the highest).
Tip:
To reduce the time and memory for converting data, use the same data type for all
the operands of an instruction.
Convert SINT or INT to DINT or DINT to LINT
A SINT or INT input source tag gets promoted to a DINT value by a sign-
extension for Source Tag. Instructions that convert SINT or INT values to DINT
values use one of the following conversion methods.
This conversion
method
Converts data by placing
Sign-extension The value of the leftmost bit (the sign of the value) into each bit position to the left of the existing bits until there
are 32 or 64 bits.
Zero-fill Zeroes to the left of the existing bits until there are 32 or 64 bits.
Logical instructions use zero fill. All other instructions use sign-extension
To Next Page
Loading...
Need help?
General
