Double Word Increment and Decrement Integer Math

Inputs/Outputs Operands Data Types
IN VD, ID, QD, MD, SD, SMD, LD, AC, HC, Constant, *VD, *AC, *LD DINT
OUT VD, ID, QD, MD, SD, SMD, LD, AC, *VD, *AC, *LD DINT

Memory Ranges ENO Errors Instruction Support for S7-200 CPUs SIMATIC/International Mnemonics
The Increment Double Word and Decrement Double Word instructions add or subtract 1 to or from the input double word (IN) and place the result in OUT.

In LAD and FBD: IN + 1 = OUT

IN - 1 = OUT

Increment and decrement double word operations are signed (16#7FFFFFFF > 16#80000000).

In STL: OUT + 1 = OUT

OUT - 1 = OUT

Error Conditions that Set ENO = 0:

SM1.1 (overflow), SM4.3 (run-time), 0006 (indirect address)

These instructions affect the following Special Memory bits:

SM1.0 (zero); SM1.1 (overflow); SM1.2 (negative)