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C
1.9.4)
Logic sequence
with
ON-commands
A logic sequence
with
ON-commands
effects
a parallel switching
of contacts.
These contacts
are normally
closed.
This corresponds
to an OR-Gate
with
inverted
operarid.
PLC-Programme
Gating-logic
Abbreviated
symbol
ON El
"O"-
ON E2
Yz
Al
El -
Al
13 -----+
t-Al
Truth
table
El
E2
1 Al
Contact
example
t
f
El
ibb?-i
E2
It can be deduced
frorn the truth
table that this logic element
is behaving 21s a NAND-function.
This also
follows
the rules governing
the Boolean
Algebra:
Fl
+
-
-____
E2
=
El
E2
Examples:
a)
b)
t
+2&V
rt
1
Lamp 31 should
illuminate
in the event of contact
S14 being open.
PLC-Programme:
ON El9
=
A53
The relay K14 should energise when contact
S4 or Sl 1,
or both, are open.
PLC-Programme:
ON E34
ON E48
=
Al7
This PLC-programme
effects
the following
Th s PLC-programme
effects
the following
switching:
switching:
+2&V
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