Siemens SIMATIC S7 System Manual page 306

Program instructions
7.8 Math
Example: Increment and decrement
LAD
Increment/decrement operations from the LAD example
Increment word
Data address
Decrement double word
Data address
306
STL
Network 1
LD I4.0
INCW AC0
DECD VD100
IN
125 + 1
AC0
128000 - 1
VD100
System Manual, V2.3, 07/2017, A5E03822230-AF
OUT
= 126
AC0
= 127999
VD100
S7-200 SMART