PLC Flashcards
What is a PLC
PLC is a device which is capable of being programmed to perform a controlling function
What is the principle function of input interface?
To receive and convert field signals into a form that can be used by the CPU
The input interface provides a connection to…
The machine or process being controlled
Where is fundamental operating information stored in?
It is stored in the processor’s memory as a pattern of electrical charges (bits) that are organized into basic working groups called words
Define analog signal
A signal that depends entirely on magnitude to express a quantity
What are analog signals used for
Analog signals are used to transmit various levels of a signal
The output interface…
Connects the CPU to the process and produces the control signals
A PLC device is capable of being to perform a ____ function
Control, Controlling
What are some common functions implemented on PLC’s
Arithmetic, Counting, Data Communications
Conventional time delay relays produce a processing delay of
0.15 Seconds
How much memory was used in the earliest PLC’s?
1kB
How many companies manufacture PLC’s?
> 50
What year did NEMA release it’s standard for PLC’s?
1978
The PLC system that interacts with the user is called a(n)___
Terminal
Components of a PLC include
Input interface, Output interface, Programs
