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A)
Introduction
Logiccircuits
operate
in binary
i.e. two unique,
dedicated
switching
states.
The two possible
logic states will be represented
by the figures
"1"
and "0"
in this description.
Example:
Switch
closed
= "1"
Switch
open
= "0"
'
Lamp on
= "1"
Lamp off
= "0"
This relationship
can be represented
with
the aid of a function
table (truth
table). The switch
state is
represented
as an input variable
(operand)
El and the lighted lamp as a logic result Al.
Truth
Table:
Digital switching
signals can be combined
(logic circuits).
The basic logic elements
in the switching
algebra are:
AND
OR
NOT
The logic results of digital switching
signals can be realised in the following
ways:
.through
relays
.through
integrated
circuits
.through
software
programmes
Since the implementation
of logic sequences
using software
programmes
allows
greater flexibility
in the event
of alterations,
the programmable
interface
(PLC = Programmable
Logic Controller)
has gained ground
in the
application
to machine
tool control.
The PLC is integrated
in the HEIDENHAIN
control
TNC 1510, giving the following
advantages:
.The signals between
NC and PLC are markers,
making
more input and output
signals possible
and the control
more flexible
.The hardware
interface
is simplified
.As the PLC programme
can be entered
at the control,
an ex.ternal programming
station
is unnecessary
.When programming
,the PLC functions,
an immediate
check
is possible
.Machine
faults can b'e displayed
on the screen
Please note:
We are constantly
working
on the further
development
of out TNC-Controls
and a certain
control
may deviate
from the versions
described
within
this manual.
5
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