Statement List (STL) - DCE FEL ČVUT v Praze

14.10 DEC Decrement ACCU 1-L-L
Format
Description
Status word
Example
DEC
Address Data Type Description
8-bit integer
constant
Accumulator Instructions
Constant subtracted from ACCU 1-L-L; range
from 0 to 255
DEC (decrement ACCU 1-L-L) subtracts the 8-bit integer from the
contents of ACCU 1-L-L and stores the result in ACCU 1-L-L. ACCU 1-L-H, ACCU
1-H, and ACCU 2 remain unchanged. The instruction is executed without regard to,
and without affecting, the status bits.
Note
These instructions are not suitable for 16-bit or 32-bit math because no carry is made
from the low byte of the low word of accumulator 1 to the high byte of the low word of
accumulator 1. For 16-bit or 32-bit math, use the +I or +D. instruction, respectively.
BR CC 1 CC 0 OV OS OR STA RLO /FC
writes: - - - - - - - - -
STL Explanation
L MB250 //Load the value of MB250
DEC 1 //Instruction "Decrement ACCU 1-L-L by 1"; store result in ACCU 1-L-L.
T MB250 //Transfer the contents of ACCU 1-L-L (result) back to MB250.
Statement List (STL) for S7-300 and S7-400 Programming
A5E00706960-01 14-9