Siemens S7-200 User Manual download pdf (Page 17)

Normally-Closed (NC) Contact

To allow the latching function to be termi-

nated again, input I0.1 is to work like a

break in the current path when operated.

If a current path is interrupted

(i.e. state "0" exists) when a switch is

operated, this is referred to as an

NC contact.

Consequently, an element must be

inserted which works as an NC contact

in the ladder diagram when there are

24 V DC ("true") at input I0.1.

Latching

- Introduction

- Normally-Closed (NC) Contact

- Solution Description and Test

- A Different Take on Latching

NC contact:

This is what the finished

latching function looks

like!

Below is the principle of

operation shown as a

timing chart.

Complete an NC contact for switch S1

at I0.1. This is described on the next

page!

t = time till the results of logic operations are trans-

ferred to the outputs (= response time).

Off priority

Latching Revision

Pulse-Oper-

ated Switch

Off-Delay

Timer

Sequencer Appendix

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 73 74

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Siemens S7-200 User Manual Page 17