Statement List (STL) - DCE FEL ČVUT v Praze

Conversion Instructions
3.10 NEGI Twos Complement Integer (16-Bit)
Format
Description
Status word
Example
NEGI
NEGI (twos complement integer) forms the twos complement of the 16-bit value in
ACCU 1-L. Forming the twos complement inverts the value bit by bit, that is, zeros
replace ones and ones replace zeros; then a "1" is added. The result is stored in the
low word of accumulator 1. The twos complement instruction is equivalent to
multiplication by "-1." The status bits CC 1, CC 0, OS, and OV are set as a function of
the result of the operation.
BR CC 1 CC 0 OV OS OR STA RLO /FC
writes: - x x x x - - - -
Status word generation CC 1 CC 0 OV OS
Result = 0 0 0 0 -
-32768 = 1 1 0 0 -
Result = 2768 0 1 1 1
STL Explanation
L IW8 //Load value into ACCU 1-L.
NEGI //Form twos complement 16-bit.
T MW10 //Transfer result to MW10.
Contents ACCU1-L
Bit 15 . . . . . . . . . . 0
before execution of NEGI 0101 1101 0011 1000
after execution of NEGI 1010 0010 1100 1000
Statement List (STL) for S7-300 and S7-400 Programming
3-10 A5E00706960-01