Unused Inputs; To Create A Circuit Logic In Logo! - Siemens Logo! Manual

Programming LOGO!
Note
Although you have four inputs available for logic opera-
tions (Basic functions, see Chapter 4.2), most of the views
will only show three inputs for reasons of clarity. You pro-
gram this fourth input and assign parameters just like you
do with the other three inputs.
To create a circuit logic in LOGO!, start at the output.
The output is the load or relay that is to be switched.
Convert the circuit logic into blocks by working through the
circuit, starting at the output and ending at the input:
Step 1: The make contact S3 is interconnected in series to
output Q1 and to a further circuit element. A series connec-
tion corresponds with the AND block:
I3
x
Step 2: S1 and S2 are connected in parallel. A parallel cir-
cuit corresponds with the OR block:
I1
I2
x

Unused inputs

The circuit program automatically assigns the unused con-
nectors a status that ensures proper functioning of the rele-
vant block. If you like, you can label unused connectors
with an 'x' identifier.
In our example we shall use only two inputs of the OR
block and two inputs of the AND block; the relevant unused
third and fourth inputs are identified at the connector with
an 'x'.
Now connect the I/Os to the LOGO! .
64
&
w1
I3
x
Q1
&
Q1
LOGO! Manual
A5E00380835-01