plc ch 1&2&5&6

individual outputs of a typical AC output interface module usually have a maximum current rating of about?

1A to 2 A

A/An ___ input or output is a continuously variable signal within a designated range.

Analog

When a module is slid into a PLC rack, it makes electrical connections with the?

back plane

The___________ instructions always interpret a 1 status as true and a 0 status false. a. XIC b. XIO c. contact d. all of these

XIC

PLC proprietary architecture a. is the opposite to open architecture b. makes it more difficult to connect to devices made by other PLC manufacturers c. does not allow programs to be interchanged between different PLC manufacturers. d. all these above

all these above

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

Input module in slot 2, terminal 4

The light source used in most industrial photoelectric sensors is a: a. LED b. phototransistor c. photovoltaic cell d. miniature incandescent lamp

LED

The PLC power supply module normally is rated to provide the power for: a. all field devices b. input field devices only. c. output field devices only. d. PLC backplane and I/O modules

PLC backplane and I/O modules.

Parallel connections of ladder logic are typically called: a. rungs b. networks c. coils d. branches

branches

A ladder rung is said to have logic continuity when a. at least one left-to-right true logical path exists b. all input instructions are at a logic 1 c .all input instructions are at a logic 0 d. both a and b

at least one left-to-right true logical path exists

_____ is a type of memory commonly used for temporary storage of data that may need to be quickly changed.

RAM

_____memory is used by the PLC's operating system.

ROM

An electromagnet control relay is basically a(n): a. electromagnet used to switch contacts b. electromagnet used to relay information c. manually operated control device d. pressure-operated control device

electromagnet used to switch contacts

The addressing format for inputs and outputs is standard for all plc models.

false

The greater the scan time, the faster the PLC can react to changes in inputs.

false

one disadvantage of modular I/O is its lack of flexibility

false

A control management PLC application normally requires a: a. micro-size PLC b. small-size PLC c. medium-size PLC d. large-size PLC

large-size PLC

The output interface module connects to: a. sensing devices such as switches or pushbuttons b. load devices such as lamps or solenoids c. a programming device such as a computer. d. all these above

load devices such as lamps or solenoids

Programmable logic controllers are categorized according to the: a. number of I/O points b. current rating of I/O modules c. power rating of the I/O modules d. cost of the I/O modules

number of I/O points

The PLC chassis comes in different sizes according to the:

number of slots they contain

All servo motors a. operate in the closed loop mode b. operate in the open loop mode c. operate without feedback d. both b and c

operate in the closed loop mode

Signals going out from the PLC to control field devices are called?

outputs

________ is the process of reading inputs, executing the program, and setting outputs on a continuous basis.

plc scan

The memory organization of a PLC can be divided into two categories? a. input and output image files b. timer and counter files c. program and data files d. control and integer

program and data files

a ________ is a ex of a device that could be used to provide a discrete input to a plc.

pushbutton, limit switch, selector switch

the following statement does not apply to the optical isolator circuit used in I/O modules is that is

rectifies AC signals.

PLCs were originally designed as replacements for

relay control panels

Plcs were originally designed as replacements for? a. micro computes b. relay control panels c. analog controllers d. digital controllers

relay control panels

The force applied to a strain gauge causes it to bend and change its: a. temperature b. resistance c. voltage d. current

resistance

To operate the program, the controller is placed in ____ mode.

run

Each complete horizontal line of a ladder diagram is generally referred to as a a(n): a. rung b. branch c. input d. output

rung

The symbol -| |- in a ladder logic diagram: a. can be thought of as a normally open contact b. represents a capacitor c. is always at logic 0 d. is always at logic 1

can be thought of as a normally open contact

In ladder logic programs, outputs are represented by: a. contact symbols b. coil symbols c. schematic load device symbols d. either a or b

coil symbols

A limit switch is usually actuated by: a. hand b. pressure c. contact with an object d. an electromagnet

contact with an object

When a program rung consist of an output instruction only, the output would then be: a. continuously ON b. continuously OFF c. shorted d. both a and c

continuously ON

At the start of the PLC scan the: a. status of all inputs read b. status of all outputs is updated c. program is executed d. diagnostics and communications tasks are executed

status of all inputs are read.

a(n) _________ converts electrical pulses applied to it into discrete rotor movements. a. tachometer b. solenoid c. stepper motor d. electronic magnetic flowmeter

stepper motor

When the PLC is required to operate the user program without energizing any outputs, it is placed in the _________ mode. a. run b. clear memory c. program d. test

test

The I/O system provides an interface between:

the CPU and field equipment.

A normally open limit switch is wired to an input module, and programmed using XIO instruction. The instruction will be true when: a. power is applied and the PLC is in the run mode b. the limit switch is closed c. the limit switch is open d. never

the limit switch is open

The abbreviations NO (normally open) and NC (normally closed) represents the electrical state of switch contacts when: a. power is supplied b. power is not applied c. the switch is actuated d. the switch is not actuated

the switch is not actuated

Which of the following input field device would most likely be used with an analog interface input module

thermocouple

The scan time is the time required to: a. to record the status of all input devices b. to record the status of all output devices c. to execute one cycle of the total program d. for the information to pass from input to output

to execute one cycle of the total program

A plc is basically a computer designed for use in electrical control applications.

true

An electromechanical relay uses electromagnetism to operate contacts.

true

Hysteresis for sensors means that there is an on point and a separate off point.

true

If any input signal changes state very quickly, it is possible that the controller may never be able to detect the change.

true

LED light sources used in photoelectric sensors normally emit a continuous beam of light.

true

Ladder logic is a symbolic language

true

Strain gages are used for pressure/force sensing.

true

The input/output system forms the interfaces through which field devices are connected to the controller.

true

The instruction set for a particular PLC lists the types of instructions supported

true

The memory organization of a plc is often called a memory map.

true

The number and type of I/Os cannot be changed in a fixed PLC

true

most instructions require one word of memory.

true

on some plc models, branches can be established at both the input and output portions of a rung.

true

plug in compartments allow I/O modules to be easily connected and replaced

true

plug-in compartments allow I/O modules to be easily connected and replaced

true

removing the programming device from the PLC will not affect the operation of the user program

true

the programmable controller operates in real time

true

the status of input and output devices is stored in a data table.

true

the user program contains the logic that controls the machine operation.

true

weight strain gauges operate by detecting small changes in temperature.

true

when dealing with a PLC memory one K of memory represents 1024 bits

true

A programmed XIC instruction: a. with a bit status of 1 will have logic continuity b. with a bit status of 0 will have logic continuity c. is examined for an OFF condition d. both b and c

with a bit status of 1 will have logic continuity

A proximity switch can be actuated: a. without any physical contact b. by a change in light intensity c. by a change in capacitance d. an electromagnet

without any physical contact

a ________ is a ex of an actuator that could be controlled by discrete output from a PLC

Motor starter

Capacitor proximity sensors: a. are actuated by both conductive and non conductive materials b. are actuated by conductive materials only c. produce an electromagnetic field d. have a long sensing range.

are actuated by both conductive and non conductive materials

The PLC program is stored in the processor modules

memory

The term central processing unit is often used interchangeably with the term

processor

Ultrasonic sensors operate using high frequency light waves.

false

contacts are output instructions

false

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

false

series logic could also be called OR logic

false

the number of I/O points does not affect the memory size required for a PLC installation

false

___________I/Os are typical of small PLCs that come in one package with no separate removable units. a. fixed b. modular c. digital d. analog

fixed

When there is a true logic run path, all parallel outputs in the rung become true.

true

The symbol -( )- in a ladder logic diagram represents a: a. set of normally closed contacts b. virtual relay coil c. seal in circuit d. field input sensing device

virtual relay coil

The most common form of memory used to store, back up, or transfer PLC programs is:

Flash EEPROM and EEPROM

Which of the following is not a function of a PLC programming device?

To execute the user program

The examine if open instruction: a. is also known as the Examine-off instruction b. is also known as the XIO instruction. c. looks and operates like a normally closed relay contact. d. all of these

all of these

The output energize instruction: a. is also known as the OTE instruction b. signals the PLC to energize or de energize the output c. looks and operates like a relay coil d. all of these

all of these

The programming device: a.is used to enter the program into the memory of the processor. b. is commonly a personal computer c. can be a handheld device d. all of these

all of these

Unlike personal computers, PLCs are: a. equipped with input and output modules b. equipped with a control programming language c. designed for the industrial environment d. all of these

all of these

Which of the following is a factor in determining the total scan time? a. length of the ladder program b. type of instructions executed c. speed of the processor d. all of these

all of these

Which of the following standard PLC programming languages is a graphical langauge? a. function block diagram b. ladder diagram c. sequential function chart d. all of these

all of these

A programmed XIO instruction: a. with a bit status of 1 will not have logic continuity. b. is examined for an off condition c. is examined for an ON condition d. both a and b

both a and b

The addressing format used with PLCs: a. is standard for all PLCS b. indicates what PLC input is connected to what input device. c. indicates what PLC output is connected to what output device. d. both b and c

both b and c

The programming device must be connected to the controller: a. at all times b. when entering a program c. when monitoring a program d. both b and c

both b and c

incoming control signals to a PLC are called a

input

The status bit of switches and pushbuttons connected to a PLC are stored in the: a. input image table file b. output image table file c. user program d. all of these

input image table file

A contactor a. is another name for a relay b. is designed to handle heavy power loads. c. always has an overload relay physically and electrically attached d. is a physically small realy

is designed to handle heavy power loads.

Basically, the function of a PLC is to a. amplify various weal signal sources b. control a high- voltage out put with a low voltage input c. control the speed of motors d. make logical decisions and control outputs based on them

make logical decisions and control outputs based on them

The output data is sent to the a. output field devices b. output module c. input module d. ladder program

output field devices

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

output is active.

Branch input instructions are used to create a : a. series path of input instructions b. parallel path of input instructions c. serial connection of input modules d. parallel connection of input modules

parallel path of input instructions

Which module of the PLC is responsible for performing logical operations? a. processor b. input c. output d. power supply

processor

A tachometer normally refers to a(n) _________ used for speed measurement. a. load cell. b. capacitive proximity sensor c. ultrasonic sensor d. small generator

small generator

software installed and run on a personal computer can be used to write a PLC program

software installed and run on a personal computer can be used to write a PLC program

A________ converts light energy directly into electric energy. a. LED b. phototransistor c. solar cell d. photoconductive cell

solar cell

The rung condition and OTE instruction are false if no logical continuity path has been established.

true

The status of the OTE instruction is set to 1 to energize the output and to 0 to de energize the output

true

There is more than one correct way to implement the ladder logic for a given control process.

true

There may be a limit to the number of series contact instructions that can be included in one rung of a ladder logic program.

true

When the XIO instruction is associated with a physical input, the instruction will be set to 1 when there is no input voltage applied to the terminal.

true

a PLC power supply module does not normally supply power to the field device

true

a(n)____ operates by sending sound waves toward a target and measuring the time it takes for the pulses to bounce back. a. pressure sensor b. bar code scanner c. ultrasonic sensor d. flowmeter

ultrasonic sensor

In event of a power interruption, a _____ is used in some processors to provide power to the RAM.

capacitor

If a PLC has a total scan time of 10ms and has to monitor a signal that_____ then the controller may not detect this change. a. changes state once in 20ms b. is fast c. is constantly changing d. changes state twice in 5 ms

changes state twice in 5 ms

Modifying relay type process control circuits usually involves changing a. circuit wiring b. input circuit modules c. output circuit modules d. circuit operating voltage levels

circuit wiring

changes to hardwired relay control systems usually require some _____ of the system.

circuit wiring

The last element to be entered on a ladder rung is a: a. coil b. contact c. XIC instruction d. XIO instruction

coil

An encoder is used to: a. encode signals from a scanner b. decode signals from a scanner. c. change DC to AC d. convert motion into a digital signal

convert motion into a digital signal

one function of a PLC input interface module is to

convert signals from the processing unit into values that can be used to control the machine or process

An actuator is a device that: a. changes AC to DC b. changes DC to AC c. converts an electrical signal into mechanical movement d. converts mechanical movement into an electrical signal

converts an electrical signal into mechanical movement

A normally closed (NC) relay contact is closed when current flows through the coil.

false

A through beam photo electric sensor is used to detect the light beam reflected from the target.

false

A thru-beam sensor has the shortest sensing range of the three types of photo sensors.

false

All servo motors operate in open loop.

false

An inductive proximity sensor is actuated by conductive and non conductive materials

false

Each individual contact instruction can be used only once throughout the program.

false

Having each field device wired back to a common point on a plc module makes it more difficult to check the operation of the field devices

false

In a magnetic motor starter, the control circuit is required to handles the full load current of the motor.

false

In general, PLC output modules are designed to switch high current loads directly.

false

In general, control relay contacts are designed to handle high currents than contacts.

false

It takes the processor exactly the same amount of time to examine different types of instructions.

false

PLC systems usually require as much space in an enclosure as equivalent hardwired relay systems.

false

Parallel logic could also be called AND logic.

false

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

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

false

When the XIC instruction is associated with a physical input, the instruction will be set to 1 when there is no input voltage applied to the terminal.

false

all plc manufacturers organize their memories in the same way.

false

Scan time varies with program content length.

true

The scan time is the time required for one complete execution of the user program.

true

Which module of the PLC connects directly to field devices such as pilot lights, motor starters, and solenoids? a. input b. output c. power supply d. memory

Output

The Allen-Bradley SLC-500 address O:3/0 refers to an:

Output module in slot 3, terminal 0.

When a field device contact connected to the input module closes: a. a logic 1 is recorded in the memory location of the coil with the same address. b. a logic 1 is recorded in the memory location of the contact with the same address. c. a logic 0 is recorded in the memory location of the coil with the same address. d. a logic 0 is recorded in the memory location of the contact with the same address.

a logic 1 is recorded in the memory location of the contact with the same address.

An inductive proximity sensor is actuated by: a. a metal object b. a light beam c. a nonconductive material d. any of these

a metal object

The most common actuator for a reed switch is: a. a permanent or electromagnet b. a light beam c. application of pressure d. a heat source

a permanent or electromagnet

The control plan stored in the PLC is called: a. a program b. a Boolean ladder c. FORTRAN d. a microprocessor

a program

The actual scan time is: a. calculated and stored in the PLC's memory b. computed each time the END instruction is executed. c. the time taken to scan inputs and outputs and execute the user program. d.all of these

all of these

Field or real-world devices refer to: a. input devices only b. output devices only c. load devices only d. all devices that are physically wired to the PLC

all devices that are physically wired to the PLC.

A human machine interface (HMI): a. allows the user to monitor a process. b. allows the user to control a process c. can provide a graphical representation of a process d. all of these

all of these

Fiber optic sensors: a. are not affected by electrical interference b. carry light signal signals c. use a flexible cable containig tiny fibers d. all of these

all of these

PLC software that runs on a personal computer can be used to: a. write a PLC program b. document a PLC program c. monitor the control process. d all of these

all of these

Solenoid valves are available to control: a. oil flow b. air flow c. waterflow d. all of these

all of these

a scan pattern examines instructions rung by rung a. horizontal b. vertical c. input d. output

horizontal

Bar code scanners are used primarily for: a. data collection b. temperature measurement c. pressure measurement d. flow measurement

data collection

The main element of an analog output module is

digital to analog converter.

Volatile memory elements can be classified as those that:

do not retain stored information when the power is removed.

An internal control relay: a. does not directly control an output field device b. is not controlled by the programmed logic c. is used primarily to control the internal power to the processor module d. is used primarily when controlling multiple output circuits

does not directly control an output field device

The central processing unit. a. looks at the inputs, makes the decisions based on the program, and sets the outputs. b. looks at the outputs, makes the decisions based on the program, and sets the inputs c. serves only to store the program in memory. d. serves only to supply power to the backplane.

looks at the inputs, makes the decisions based on the program, and sets the outputs.

The power required to operate the logic circuits of the processor unit is typically: a. low-voltage AC b. high-voltage AC c. low-voltage DC d. high-voltage DC

low-voltage DC

if there is no continuous logic path from left to right on the program rung, the output coil status is set to

0

In a typical ladder logic program, the symbols represent the_______ and the numbers represent the _______

Instructions , location address

Which of the following is not an advantage that PLCS offer over the conventional relay-type of control system? a. smaller size b. less expensive c. high current capacity d. more reliable

high current capacity

The two types of patterns used to accomplish the scan function are: a. horizontal and vertical b. left and right c. up and down d. input and output

horizontal and vertical

a discrete output interface module is designed to provide

on/off switching of the output field device

The main difference between a PLC and relay control system is that. a. different types of input devices are used b. different types of output devices are used c. different input and output voltage levels are used d. one uses hardwired relay control logic and the other uses programmable instructions

one uses hardwired relay control logic and the other uses programmable instructions

The scan is normally a sequential process of: a. reading the control logic, evaluating the outputs, and updating the inputs. b. writing the control logic, evaluating the outputs, and updating the inputs. c. reading/writing the status of inputs and updating the outputs. d. reading the status of inputs, evaluating the control logic, and energizing or de-energizing the outputs.

reading the status of inputs, evaluating the control logic, and energizing or de-energizing the outputs.

A relay usually will have only one coil but a number of different contacts

true

A selector switch is rotated to open and close contacts.

true

A small current flows through a solid-state proximity sensor even when the output is turned off.

true

An internal output does not directly control an output field device.

true

Both normally open and normally closed pushbuttons can be represented by the XIC or XIO instruction.

true

Changes to dual-in-line (DIP) package switch settings are made mainly during installation.

true

Coils are output instructions

true

Digital sensors are sometimes called discrete sensors because there are two discrete states: on or off.

true

Encoders are used in applications where positions have to be precisely determined.

true

Fiber optic sensor systems are completely immune to all forms of electrical interference.

true

Ladder logic is still the most common PLC programming language.

true

Latching relays are used when it is necessary for contacts to stay open and/or closed, even though the coil is momentarily energized.

true

Misunderstanding the way the PLC scans a program can cause programming bugs.

true

Reed switches are activated by magnetism.

true

The____________ will account for most of the total memory of a given PLC system. a. input image table file b. output image table file c. user program d. internal operating instructions

user program

Most proximity switches come equipped with an LED status indicator to: a. indicate that power is being applied to the switch b. indicate that the target is within sensing range. c. indicate a blown fuse within the switch d. verify the output switching action.

verify the output switching action.

The "ON state input voltage range" specification refers to

voltage at which the input signal is recognized as being ON.

Which of the following is not a factor effecting the memory size needed for a particular PLC installation? a. voltage rating of field devices b. number of I/O points c. size of control program d. supervisory functions required

voltage rating of field devices