Truncate (TRUNC)

When enabled, the TRUNC instruction removes (truncates) the fractional part of the Source and stores the result in the Destination.
Truncating does not round the value; rather, the non-fractional part remains the same, regardless of the value of the fractional part.
Available Languages
Ladder Diagram
Operands
IMPORTANT: Unexpected operation may occur if:
  • Output tag operands are overwritten
  • Members of a structure operand are overwritten
  • Except when specified, structure operands are shared by multiple instructions.
There are data conversion rules for mixing numeric data types within an instruction. See Data conversions.
Ladder Diagram
Operand
Data Type
Format
Description
Source
REAL
LREAL
immediate
tag
Value to truncate.
Destination
SINT
INT
DINT
LINT
USINT
UINT
UDINT
ULINT
REAL
LREAL
tag
Tag to store the result of the instruction.
Affects Math Status Flags
Conditional. See Math status flags.
Major/Minor Faults
None specific to this instruction. See
Index through arrays
for array-indexing faults.
Execution
Ladder Diagram
Condition/State
Action Taken
Prescan
N/A.
Rung-condition-in is false
Set Rung-condition-out to Rung-condition-in.
Rung-condition-in is true
Set Rung-condition-out to Rung-condition-in.
Dest = Truncated value of the Source.
Postscan
N/A.
Example
Ladder Diagram
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