J4 PLC

Question 1

List the four elements of a PLC

Answer 1

Input section
CPU section
Programming device
Output section

Question 2

Describe the input section of a PLC

Answer 2

designed to sense the state of the field devices that are wired to the input terminals.

Question 3

Describe the CPU section

Answer 3

is the “brain” of the PLC

has a battery to support essential parts of the volatile memory

Question 4

Describe the Output section

Answer 4

provides power to loads

loads must be in the range of about 10 A

Question 5

Program entry

Answer 5

can be accomplish on the screen of the PLC or with an external PC and PLC software

Question 6

Documentation

Answer 6

text descriptions for ladder diagrams

Question 7

Run Mode

Answer 7

gives the PLC the go ahead to solve the program

Question 8

Monitoring

Answer 8

PC monitors the PLC ladder diagram in real time.

Used for trouble shooting

Question 9

What is an intelligent terminal?

Answer 9

will allow a PLC program to be developed without being connected to the PLC itself

Question 10

What is a dumb terminal?

Answer 10

on that must be connected to the PLC to operate it has no stand alone capabilities.

Question 11

Hand-held programmers

Answer 11

are a type of dedicated terminal

rugged

Question 12

Advantages of a PLC

Answer 12

Reliability
Flexibility
Expandability
Accuracy
Ease of installation
Maintainability

Question 13

describe a byte

Answer 13

it is 8 bits

Question 14

whats a bit

Answer 14

one piece of information such as a 0 or a 1

Question 15

describe 16 bit

Answer 15

it is a 2 byte word

Question 16

a 16 bit machine can process

Answer 16

2 bytes at a time

Question 17

Executive memory

Answer 17

never changes and is stored on a some type of non-volatile memory

Question 18

all input and outputs must be

Answer 18

addressed properly for the CPU to be able to process them.

Question 19

a Discrete input

Answer 19

has only two states on or off

Question 20

DC input modules (sink/source)

Answer 20

sink: positive is switched in the field and the input goes positive
source: negative is switched in the field and the input goes negative

Question 21

Grounding and shielding

Answer 21

shields must be grounded at one point only

Question 22

Master control relay

Answer 22

for safety

shuts of power to all inputs and outputs

Question 23

List three items on which the scan time depends on

Answer 23

speed of the CPU
Length of program
Number of I/O

Question 24

What is required to capture high-speed switching events

Answer 24

interrupts