Programmable Logic Controllers Flashcards

1
Q

Name some of the industries PLC’s can be found in:

A

Chemical and Petrochemical
Automobile manufacturing
Metal smelting and mining
Lumber, pulp and paper
Food and beverage production

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2
Q

PLC’s are usually selected according to the number of ________ & _________ they can service.

A

Input and Output points

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3
Q

A control system of a PLC consists of:

A

Input devices - switches, thermostats
Controller - hard wired or software program
Output devices - relays, solenoids that control operating devices (pumps, fans, valves)

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4
Q

State the four main advantages of PLCS

A

Lower overall cost
Programmability
Reliability
Expandability

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5
Q

Name the four main hardware components of a PLC:

A

Backplace
Power Supply
Processor (CPU)
Input/Output (I/O)

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6
Q

Does a PLC have to a chassis connected to the backplane?

A

No, the backplane can be disassembled and assembled with or without a chassis.

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7
Q

A means is required for the CPU to communicate with other components and and to distribute power for internal operation. This is done through the _____________

A

Backplane

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8
Q

A PLC that is a complete unit is often called a ____ ____

A

Shoe box PLC

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9
Q

The primary functions of a PLC processor are to:

A

Read and store the status of all the input devices
Execute the user program by solving the programs logic
Update the status of all the outputs

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10
Q

The processor of a PLC carries out its functions in a sequence called the ______________ _____

A

Processor Scan

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11
Q

Whats doe RAM, ROM and EEPROM stand for?

A

RAM- random access memory
ROM- read only memory
EEPROM- electrically erasable programmable memory

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12
Q

Name an example of an EEPROM device

A

USB
Memory Cards

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13
Q

Special I/O modules are used for a variety of control functions. Name an example:

A

Position Control
High Speed Counters
Temperature Controls
Proportional Integral Derivative Control (PID)
Fuzzy Logic Control
Identification Sensors (ID)
Analog I/O

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14
Q

Describe a data highway.

A

A data highway is a local area network (LAN) cabling that connects a number of PLCS, or PLCs and PCs, allowing them to exchange programs and data.

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15
Q

A Remote I/O is used to:

A

Reduce the amount of cabling between the PLC & I/O devices

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16
Q

Discrete input and output circuits are electrically isolated from the actual circuitry that is internal to the processor module and backplane of the PLC. This is most often done by ____________ _______

A

Optoisolating devices - inputs/outputs from discrete device changed into lightbeam by the input/output modules.

17
Q

For output circuits that require large currents than can be handled by the solid state electronic switch, a relay coil is operated by the solid state switch instead. This relay is called an __________ _______

A

Interposing Relay

18
Q

You may be required to install analog cables for analog input and output devices. The most common type of cable is:

A

Shielded Twisted Pair (STP)
Conductor size may be as small as #22 AWG

19
Q

Name the five PLC programming languages,
And what two categories there are:

A

Graphics based -Ladder Diagrams (LD) , Function Block Diagrams (FBD) and Sequential Function (or flow) Chart (SFC)

Text based - Structured Text (ST) , Instruction Lists (IL)

20
Q

The most common PLC programming language is:

A

Ladder Diagram

21
Q

Function Block Diagrams are commonly used where in the world?

A

Europe

22
Q

Sequential Function/Flow Charts are used for large-process controls where complex functions take place. T or F?

A

True

23
Q

Hand-held PLC programmers at one time were commonly using what programs?

A

Text based programs

24
Q

What PLC language is similar to the computer programming language called Basic?

A

Structured Text (ST)

25
Q

Instruction List programs are similar to assembler language programs. T or F?

A

True