Siemens S7-400 Service Manual download pdf (Page 55)

Conversion Instructions

Ladder Logic (LAD) for S7-300 and S7-400 Programming

A5E00706949-01

3-11

3.11 NEG_DI Twos Complement Double Integer

Symbol

NEG_DI

ENOEN

IN OUT

Parameter Data Type Memory Area Description

EN BOOL I, Q, M, L, D Enable input

ENO BOOL I, Q, M, L, D Enable output

IN DINT I, Q, M, L, D Double integer input value

OUT DINT I, Q, M, L, D Twos complement of IN value

Description

NEG_DI

(Twos Complement Double Integer) reads the content of the IN parameter

and performs a twos complement instruction. The twos complement instruction is

equivalent to multiplication by (-1) and changes the sign (for example: from a

positive to a negative value). ENO always has the same signal state as EN with the

following exception: if the signal state of EN = 1 and an overflow occurs, the signal

state of ENO = 0.

Status word

BR CC 1 CC 0 OV OS OR STA RLO /FC

writes: x x x x x 0 x x 1

Example

Q 4.0

I 0.0

MD8

NEG_DI

ENOEN

IN OUT

MD12

NOT

If I0.0 is "1", then the value of MD8 with the opposite sign is output by the OUT

parameter to MD12.

MD8 = + 1000 results in MD12 = - 1000.

The output Q4.0 is "1" if the conversion is not executed (ENO = EN = 0).

If the signal state of EN = 1 and an overflow occurs, the signal state of ENO = 0.

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Siemens S7-400 Service Manual Page 55