LD Language Elements

Discrete Inputs

Description

The Discrete Inputs can be used exclusively as contacts in the program.

 

These contacts represent the status of the input for the smart relay connected to a

 

sensor (push button, switch, sensor, etc.).

 

The contact number corresponds to the number of terminals of the associated input:

 

1 to 9, then A to R (except for letters I, M and O) according to the smart relay and

 

the possible extension.

Use as a Contact

 

 

 

 

 

 

 

This contact may use the direct state of the input (normally open mode) or its inverse

 

state (mode normally closed), see below.

 

Normally open mode:

 

Symbol of a normally open contact:

 

 

 

 

 

 

 

 

 

 

I -

 

 

 

 

 

 

 

 

 

 

 

 

 

A normally open contact corresponds to the use of the direct state of the input. If the

 

input is supplied, the contact is said to be conducting.

 

Example: Using a pushbutton to switch a lamp on and off.

 

 

 

 

 

 

 

 

 

 

I1

 

 

 

Q1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

If input 1 is supplied, contact I1 is closed, and coil Q1 is activated.

Normally closed mode:

Symbol of a normally closed contact:

i -

A normally closed contact corresponds to the use of the reverse state (logical complement of the direct state) of the input. If the input is supplied, the contact is said to be non-conducting.

Example: Controlling a lamp using an input in reverse state.

i1 [Q1

If input 1 is supplied, contact i1 is open, and coil Q1 is non-activated.

SR2MAN01 11/2007

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Schneider Electric SR2MAN01 user manual Discrete Inputs, Use as a Contact, Normally open mode, Normally closed mode, I1 Q1