PLC midterm

Used as emergency or contact switches.

foot switch

Consists of an actuator that is mechanically linked to a set of contacts.

limit switch

Has registers that are used by advanced PLC instructions such as bit shift and sequencer instructions.

bit

Holds 256 words (R6:0 to R6:255) that are used as control registers for advanced PLC instructions such as bit shift and sequencer instructions.

control

OR

NOT

AND

NOR

XNOR

XOR

The four major components of a PLC power supply are a line conditioner or varistor, transformer/rectifier unit, RC filter, and ____.

zener diode

A(n) ____ is a semiconductor device that can maintain a steady voltage level.

zener diode

The ____ segment holds the PLC ladder logic diagram.

user memory

Read only memory (ROM) holds the permanent system program.

true

The arithmetic logic unit (ALU) carries out math and logic instructions.

true

Simplex channeling occurs when the DTE either transmits data to or receives data from the DCE.

true

Sourcing occurs when the current flows out of the PLC port and sinking occurs when the current flows into the PLC port.

true

The positional value of 2 in the decimal number 12,345 is 2 × 10⁴.

false

The SLC 500, MicroLogix, and PLC-5 are examples of 16-bit PLCs.

true

Traditional PLCs allocate a portion of the controller’s physical memory segmented into data files for the storage of program-related information.

true

A proximity switch uses a light-emitting diode (LED) and a phototransistor.

true

Flow switches are used to open and close contacts in response to changes in liquid level.

false

Inductive sensors detect the presence of nearby metallic objects by measuring changes in magnetic fields.

true

A relay is a device that acts on the same basic principle as the reed switch.

true

According to rule nine, the location of each contact associated with a coil can be recorded by the left-hand rail near the coil.

false

Each output device can only be represented once in a relay logic diagram.

true

You can place two or more input instructions in series in a PLC ladder logic rung.

true

Input address instructions may be used two or more times in a PLC ladder logic diagram.

true

Output address instructions may be used two or more times in a PLC ladder logic diagram.

false

EEPROM is an acronym for ______________________________.

Electrically Erasable Programmable Read-Only Memory

EPROM is an acronym for ______________________________.

Erasable Programmable Read-Only Memory

SRAM is an acronym for ______________________________.

Static Random Access Memory

DRAM is an acronym for ______________________________.

Dynamic Random Access Memory

Ports that are either open (off) or closed (on) are ______________________________ input ports.

Discrete

Output ports that are either energized (on) or de-energized (off) are ______________________________ output ports.

Discrete

The ______________________________ in the microprocessor is used to carry out math and logic instructions.

Arithmetic Logic Unit

A(n) ______________________________ converts the analog input signals to digital signals.

ADC

A(n) ______________________________ converts the digital output signals back to analog

DAC

SLC is an acronym for ______________________________.

Small Logic Controller

SRAM uses a(n) ______________________________ to hold a data bit.

flip-flop

CPU is an acronym for ______________________________.

Central Processing Unit

A(n) ______________________________ diode is a semiconductor device that can maintain a steady voltage level.

zener

To physically isolate the CPU from the input device, a(n) ______________________________ is used to input the DC signal to the CPU board.

optoisolator

PPI is an acronym for ______________________________.

Point-to-Point Interface

UVEPROM is an acronym for ______________________________.

Ultraviolet Erasable Programmable Read-Only Memory

A(n) ______________________________ is a sequential digital device that generates a different output for every input on the next clock pulse.

counter

BIOS is an acronym for ______________________________.

Basic Input/Output System

The MPU uses ______________________________ memory to speed up the data transfer while it is executing a program.

cache

The software that resides in ROM is called ______________________________.

firmware

A microprocessor unit (MPU) uses a(n) ______________________________ to enable ROM, RAM, I/O port devices, and support chips.

address bus

Allen-Bradley SLC 500 PLCs have Channel ______________________________ and Channel ______________________________ that can be used for communications.

0 and 1

A unit for measuring the speed of serial communication transmission is the ______________________________ rate.

baud

Transmitted data that have an even number of ones uses ______________________________ parity.

even

In communication systems, DTE stands for ______________________________.

Data Terminal Equipment

In communication systems, DCE stands for ______________________________.

Data Communication Equipment

The ______________________________ instruction allows the system to run and allows the program to be modified while the system is running.

run

A sinking input device must be connected to a(n) ______________________________ input module port.

sourcing

A sourcing output device must be connected to a(n) ______________________________ output module port.

sinking

The ______________________________ is a rack that serves as an electrical backplane for a PLC.

chassis

The ______________________________ Allen-Bradley SLC 500 PLCs give you the option of chassis, power supply, processor, and I/O modules.

modular

The three different types of PLC programming modules are handheld, dedicated, and ______________________________.

computer-based

Digital, or variable, output modules use ______________________________ ICs to convert digital data supplied by the PLC processor to scalable voltage or current output.

DAC

A(n) ______________________________ check is used to find transmission errors due to lost or changed bits.

parity

The number of unique symbols used to represent numbers in a particular number system is indicated by the ____________________.

base

In the PLC world, a device on a network is referred to as a(n) ____________________.

node

ControlLogix has a basic memory allocation of ____________________ bits, or a double word.

32

One method of converting binary to hexadecimal is to start with the least significant bit (LSB) and break the binary number into groups of ____________________ bits.

4

A 16-bit word is made up of two bytes, an upper and a lower byte. Each byte is broken down into an upper and a lower ____________________.

nibble

A(n) ______________________________ sensor detects the presence of metallic objects by measuring changes in magnetic fields.

inductive

A(n) ______________________________ sensor produces a small AC voltage signal.

magnetic

Power relays are often called ______________________________.

contactors

A relay coil in a low-power control circuit is energized by applying ______________________________ voltage to the coil terminals.

DC

Two types of motor overload relays are available in industry: temperature overload relays and ______________________________ overload relays.

magnetic

In an optical sensor, a(n) ______________________________ is used to generate light beams in the visible and invisible spectrums using light-emitting diodes (LEDs) and laser diodes.

emitter

A(n) ______________________________ pushbutton or switch is always open—until it is forced to close.

normally open

A(n) ______________________________ pushbutton or switch is always closed—until it is forced to open.

normally closed

The term ______________________________ refers to the number of places in which a switch opens or breaks the circuit.

pole

Pushbuttons and switches, also called ______________________________ input devices, are independent devices that either allow or disallow electric current to flow through them.

discrete

Momentary pushbuttons, also called ______________________________ pushbuttons, change their states from open to closed or from closed to open.

spring-return

Ultrasonic sensors use sound waves with frequencies above ______________________________ kHz in order to detect the distance to an object.

40

A(n) ______________________________ switch is generally used to detect the liquid level in a chemical tank or water well.

float

A(n) ______________________________ switch is used in factory environments as an emergency or contact switch when a worker is using both hands for assembling a product.

foot

In general, a relay consists of a magnetic core and its associated coil, ______________________________, spring, armature, mounting, and terminals.

contacts

A(n) ______________________________ is a control device that uses electromagnetism to convert electrical energy into mechanical motion.

solenoid

A(n) ______________________________ simply turns a motor on and off.

motor starter

The two main sections of motor starters are ______________________________ and overload protection.

contactor

A(n) ______________________________ is typically used in the control of low-power circuits or other devices.

relay

Slowly accelerating a motor from standstill to operating speed is referred to as a(n) ______________________________.

soft start

A(n) ______________________________ sensor detects an object through the change in the sensor’s dielectric.

capacitive

A(n) ______________________________ logic diagram is created to show the logical relationship between devices.

relay

The ______________________________ is used to program the programmable logic controller (PLC)

programming device

There are ______________________________ rules accepted as standard in the control industry for creating relay logic diagrams.

9

According to rule six, all the input and output devices must be placed ______________________________.

horizontally

In the relay logic diagram, ______________________________ must flow from left to right.

current

XIC is an acronym for ______________________________.

examine if closed

XIO is an acronym for ______________________________.

examine if open

An Allen-Bradley SLC 500 series PLC has ______________________________ registers with addresses from N7:0 to N7:255.

integer

A method of testing the PLC system without actually closing or opening input devices is to test the PLC in the ______________________________ mode.

force

PLC program execution, or program ______________________________, flows from left to right on each rung, starting from the top rung and continuing to the bottom rung.

scan

The main ladder logic diagram is held in ______________________________.

file 2