Statement List (STL) - DCE FEL ČVUT v Praze

Conversion Instructions
3.16 TRUNC Truncate
Format
Description
Status word
Example
TRUNC
TRUNC (conversion of a 32-bit IEEE floating-point number to 32-bit integer)
interprets the contents of ACCU 1 as a 32-bit IEEE floating-point number. The
instruction converts the 32-bit IEEE floating-point number to a 32-bit integer (double
integer). The result is the whole number part of the floating-point number to be
converted (IEEE rounding mode "round to zero"). If the number is out of the
permissible range, then the status bits OV and OS are set to 1. The result is stored in
accumulator 1.
Conversion is not performed and an overflow indicated in the event of a fault
(utilization of a NaN or a floating-point number that cannot be represented as a 32-bit
integer number).
BR CC 1 CC 0 OV OS OR STA RLO /FC
writes: - - - x x - - - -
STL Explanation
L MD10 //Load the floating-point number into ACCU 1-L.
TRUN //Convert the floating-point number (32-bit, IEEE-FP) to an integer (32-bit)
C
and round result. Store the result in ACCU 1.
T MD20 //Transfer result (double integer number) to MD20.
Value before conversion Value after conversion
MD10 = "100.5" => TRUNC => MD20 = "+100"
MD10 = "-100.5" => TRUNC => MD20 = "-100"
Statement List (STL) for S7-300 and S7-400 Programming
3-16 A5E00706960-01