Siemens S7-200 User Manual download pdf (Page 20)

A Different Take on Latching ... (1)

In PLC technology, latching is often also implemented in another

variant:

Instead of feeding back the output - as in the previous example - here the

functions "Set" and "Reset" are simply used instead. Have a look first at

the ladder diagram below.

Because of the "Set" operation - (S), a

switching pulse at I0.0 has the effect

that Q0.0 is activated in a steady state.

In contrast, because of the "Reset"

operation - (R), a switching pulse at I0.1

has the effect that Q0.0 is deactivated

again.

Latching

- Introduction

- Normally-Closed Contact

- Solution Description and Test

- A Different Take on Latching

-(S)

Set

-(R)

Reset

Steady-state

setting of value

with (S)

Resetting with

(R)

Last operation

in cycle has

priority

-( S )

R )

A "set" output or memory bit remains "set"

until it is reset by the

- (R) statement (becomes "untrue").

If the set coil and the associated reset coil of

an output both have signal "1", the last opera-

tion in the program takes priority.

The "coils" - (S) Set Q0.0 to "1"

- (R) Reset Q0.0 to "0"

are used frequently in PLC technology to switch

briefly activated outputs or bit memories on or off with

steady state by means of a series-connected contact.

Latching Revision

Pulse-Oper-

ated Switch

Off-Delay

Timer

Sequencer Appendix

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 73 74

Comments to this Manuals

No comments

Siemens S7-200 User Manual Page 20

Comments to this Manuals

Related products and manuals for TVs & monitors Siemens S7-200