Curso Basico Simatic (Ingles)

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The language of PLCs consists of a commonly used set of
terms; many of which are unique to PLCs. In order to
understand the ideas and concepts of PLCs, an understanding
of these terms is necessary.
A sensor is a device that converts a physical condition into an
electrical signal for use by the PLC. Sensors are connected to
the input of a PLC. A pushbutton is one example of a sensor
that is connected to the PLC input. An electrical signal is sent
from the pushbutton to the PLC indicating the condition (open/
closed) of the pushbutton contacts.