PLC TEST 1

How much memory comes with the processors in the workstations in our lab

16 K

Typically a word in a PLC is

16 bits

Address

A label or number that indicates where a certain piece of information is located in a PLC's memory

Seal-in circuit

A method of maintaining current flow after a momentary switch has been pressed and released

Interlox

A method of using logic in a PLC program to cause an output to turn on or off only if a certain input or output are in a desired condition. Used for sequencing and safety

Field or real-world devices refer to

All devices physically wired to the PLC

A signal which can vary Continuously is called...

Analog

Hardwired logic is programmable and easily changed

False... PLC ladder logic is programmable and easily changed

What is ScanTime

The time required for one full cycle, provides a measure of the speed of response of the PLC

The programming device must be connected to the controller to run the program

True programming devices used to enter desired program into the memory of the processor

The programmed latching relay instruction is retentive that is if the relay is latched it will unlatch if power is lost and then restored

False... Programmed latching relay instruction is retentive if the relay is latched it will remain latched even if power is lost and then restored

The input image table file is changed to reflect the current status of input devices during the program scan phase of operation

False... The input image of table file is changed to reflect the current status of input devices during the I/O scan phase of operation

The advantage of using a sensor that uses voltage...

Is that these devices are cheaper to produce

PLC operating cycle

During each operating cycle of the controller examines the status of input devices, executes the user program, and it changes outputs accordingly. The completion of one cycle of the sequence is called a scan

Combination control processes

For processes that require operations to be performed without regard to the order in which they are performed

In the RSLogixSoftware, where can you find a visual representation of all folders in the current project?

Project tree

Reed switches are activated by magnetism

True

An analog I/O module

Used A/D and D/A converters

Bipolar input module

Can accept signals that swing between negative and positive value

What is the advantage of choosing a voltage sensing device over a current sensing device for an analog input?

The voltage sensing device will provide a faster response time

The examine if open instruction:

It's true when is zero is stored in its address. Looks and operates like a normally closed contacts. There's also known as the XIO instruction

Programmable logic controller's are categorized according to the

Number of I/O points

An internal output does not directly control an output field device

True... An internal output is addressed to a bit in the B3 file not an address in the output image table

And or gate operates on the same principle as a:

A parallel circuit

Which model of the PLC Connects directly to the field devices such as pilot lights motor starters and solenoids

Output

An AND gate operates on the same principle as a

Series circuit

Programing device

Used to enter the desired probably

An analog module:

Uses A/D and D/A converters

The location of a specific input or output field device is identified by the processor by means of its...

Address

A _____ is an example of an actuator that could be controlled by discrete output from a PLC

Motor starter

The selector switches on our workstations are close when the switch is turned to the right

True

Current sink modules

Current flows out of the field device

The current sourcing Sensor shown must be matched with a ____ PLC input module

Current sinking

Scan time is the time required to

Execute one cycle of the total program

There is no difference between a relay schematic and a ladder logic program

False... A relay schematic uses electrical symbols for its components. A ladder logic program uses PLC instruction symbols

A unipolar module can except an input signal ranging from -5 V to +5 V

False... A unipolar module can except an input signal that varies in the positive direction only

A single rung of a ladder logic program is arranged with:

Input conditions connected from left to right with the output on the far right

The status bit of switches and push buttons connected to a PLC are stored in the:

Input image table file

The Allen - Bradley SLC - 500 address I: 2/4 refers to a

Input module in slot 2 terminal 4

Discrete devices

Inputs and outputs that have only two states: on and off

What power supply is connected to the normally open push buttons on the workstation

24 VAC

Logical rack

A chassis is a physical hardware assembly that houses devices such as I/O modules processor models and power supplies. the logical rack is an addressable unit consisting of 128 input points(bits) and 128 Output points(bits)

One function of a PLC input interface module is too...

Accept signals from field devices and convert them into signals that can be used by the processor

Input interface

Accepts signals from the machine or process devices and converts them into signals that can be used by the controller. The input interface allows status information regarding processes to be communicated to the CPU

The output energize instruction:

Looks and behaves like a relay coil. Is true when a one is stored in the memory location of its address. Is also known as the OTE instruction. Signals the PLC to energize or De-energize the output

Which of the following specifications defines the number of field inputs or outputs that could be connected to a single module?

Points per module

The memory space of a POC can be divided according to_____ and ______memory

Program, data

The PLC______Mode of operation is selected to execute the user program

Run

A___ Circuit is a method of maintaining current flow after a momentary switch has been pressed and release

Seal-in

Output interface

Converts controller signals into external signals that can be used to control the machine or process. Allows the CPU to communicate operating signals to the process devices under its control

A push button input field device would most likely be used to provide the signal to an analog input module

False... A pushbutton input field device would most likely be used to provide the signal to a discrete input module

One disadvantage of modular I/O is it's lack of flexibility

False... PLCs with the modular I/O consist of divided compartments into which separate models can be plugged this feature greatly increases the designers options and the units flexibility

The location of a specific input or output feel device is identified by the processor by means of its function

False... The location of a specific input or output field device is identified by the processor by means of its address

The electrical isolation of an analog I/O module specifies how accurately an analog value can be represented digitally

False... The resolution of an analog I/O module specifies how accurately an analog value can be represented digitally

For the AC discrete input module circuit schematic what is the purpose of the filter section

To protect against electrical noise interference

For the AC discrete input module circuit schematic what is the purpose of the optical isolator

To separate the higher of line voltage from the logic circuits

A interlock maybe used to prevent an output from turning on before another has turned on

True

An electromechanical relay uses electromagnetism to operate contacts

True

Analog modules can be either voltage sensing or current sensing

True

Sensors

Devices that measure physical quantities such as temperature, light, pressure, speed, etc.

Any device that converts energy from one form to another is called a...

Transducer

Each complete horizontal line of a ladder logic program is generally referred to as a rung

True

PLCs were originally designed as replacements for

Relay control panels

What would not be classified as a data file

Status

Current source modules

Current flows into field device

Resolution

The smallest change an input signal value that can be sensed

What is the identifying number in the model number that established the modules are compatible with the Allen - Bradley SLC - 500 family

1746

What is the processor (CPU)?

-Accepts input data from Various sensing devices -Execute the stored user program -Sense appropriate output commands to control devices

What is the file extension for a RSLogix project

.rss

How many program files does the PLC processor automatically open when a project is first created

3...The processor automatically creates to inaccessible system files and the main ladder routine program file when a project is first created

How many program files does the PLC processor automatically open when a project is first created?

3...The processor automatically creates to inaccessible system files and the main ladder routine program file when a project is first created

What is a program?

A program is a series of instructions that directs the PLC to execute actions

Sensor sensitivity

Amount of change in electrical signal that occurs for a given amount of change in the physical quantity being measured. Importance of this: determines Percision with which a PLC can monitor physical qualities, enables you to scale or calculate physical quantity being stored

What is a PLC?

An electronic device that controls output devices based on input signals and a user develop program

Program files

Areas of the processor memory where Ladder logic programming is stored individual files are identified by file number between zero and 255 files 0-2 are automatically created by the processor

Analog devices

Are inputs and outputs that can have an infinite number of states

Discrete I/O modules can be classified as

Bit oriented

Analog module addressing

Both analog inputs and outputs are word oriented. Analog data is digitalized and stored as a word ex I:2.0 or O:2.0

The advantage of using a current devices...

It is less susceptible to noise

Unipolar input module

Can accept an input signal that varies in the positive direction only

an analog signal...

Can have an infinite number of states

The output latch instruction

Can turn an output on but cannot turn the output off. Is used only to turn a bit on and latch it on. Allows the input to remain on even if the rung changes to false

How can you see what is stored in the PLC data files?

Double click on the data file name in the project tree

Program scan

During each scan cycle the processor reads all the inputs, takes these values, and energizes or De-energizes the outputs according to the user program

One function of a PLC input interface module is to

Except signals from field devices and convert them into signals that can be used by the processor

The function of the CPU is too...

Execute the operating system. Manage memory. Monitor inputs and turn on appropriate outputs.

The datafile portion of memory stores:

Input and output status. Processor status. The status of various bits and numerical data

Automatic control processes

Involves maintaining a desired set pointThese operations require some form of feedback

Standard programming language used to develop a series of instructions that direct the PLC to execute actions is

Ladder logic

________ Relays are used where it is necessary for context to stay open and or closed even though the coil is energized momentarily

Latch

The output interface module connects to

Load devices such as lamps or solenoids

The_____Instruction sets the bit to one when the wrong becomes true, and retains its state when the wrong loses continuity or a power cycle occurs

OTL

Foremost PLC systems how much memory does an examine if closed instruction require in a program file

One bit

If you want to know when one or both matching bits in two different words are on you would use the logic instruction

Or

Capacitor proximity sensors:

Our actuated by both conductive and non-conductive materials

Status indicators are provided on each output of an output module to indicate that the

Output is active

The Alan - Bradley SLC - 500 address o: 3/0 refers to a

Output module in slot three terminal four

Programmed latching circuits are retentive. This means that if power is interrupted the output will _____ when power is returned

Remain in its original on or off state

Sequential control process

Required for processes that demand certain operations to be performed in a specific order

The force applied to a strain gauge causes it to bend and change its:

Resistance

Digital to analog converter (d/a)

The analog output module receives from the processor digital data which are converted into a proportional voltage or current to control an analog field device. The analog output signal is varied under the control of the PLC program and can be used for control of an analog controlled out

What is the advantage of choosing a current sensing device over a voltage sensing device for an analog input

The current sensing device is less Susceptible to noise

Discrete means that each output or input has two states: true on... false off

True

Memory elements that store information in a PLC are called bits which refers to binary digits

True

Normally intensified rungs to an instruction on the screen of a display indicates the instruction is true and has logic continuity

True

Proximity switches usually sense the presence or absence of a target by means of physical contact

True

The rung condition and the OTE instruction on that rung or false if no logical continuity path has been established

True

Module inserted into the wrong slot could be damaged

True... He module inserted into the wrong side could be damaged by improper voltage is connected through the wiring

When the XIO instruction is associated with a physical input the instruction will be true when there is no input voltage applied to the terminal

True... When there is no voltage applied to the terminal the memory location associated with the address of the terminal will store a 0. When the XIO instruction with that address examines this bit and finds the zero the instruction will be true

In order to read I/O for a project what must you do first?

Turn on the main switch on the workstation

A ____ Operates by sending sound waves through a target in measuring the time it takes for the pulses to bounce back

Ultrasonic sensor