Download PLC Fundamentals: Q&A for 2026 Entry Final Assessment and more Exams Computer Science in PDF only on Docsity!
Verified Questions.
What is a PLC? - Answer: >> An electronic device that controls output devices based on input signals and a user develop program What is the processor (CPU)? - Answer: >>
- Accepts input data from Various sensing devices
- Execute the stored user program
- Sense appropriate output commands to control devices PLC operating cycle - Answer: >> 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 What is ScanTime - Answer: >> The time required for one full cycle, provides a measure of the speed of response of the PLC What is a program? - Answer: >> A program is a series of instructions that directs the PLC to execute actions Logical rack - Answer: >> 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)
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One function of a PLC input interface module is too... - Answer: >> Accept signals from field devices and convert them into signals that can be used by the processor Input interface - Answer: >> 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 Output interface - Answer: >> 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 The location of a specific input or output field device is identified by the processor by means of its... - Answer: >> Address Address - Answer: >> A label or number that indicates where a certain piece of information is located in a PLC's memory Current sink modules - Answer: >> Current flows out of the field device Current source modules - Answer: >> Current flows into field device
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Bipolar input module - Answer: >> Can accept signals that swing between negative and positive value Unipolar input module - Answer: >> Can accept an input signal that varies in the positive direction only Resolution - Answer: >> The smallest change an input signal value that can be sensed Digital to analog converter (d/a) - Answer: >> 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 Analog module addressing - Answer: >> Both analog inputs and outputs are word oriented. Analog data is digitalized and stored as a word ex I:2.0 or O:2. An analog I/O module - Answer: >> Used A/D and D/A converters The function of the CPU is too... - Answer: >> Execute the operating system. Manage memory. Monitor inputs and turn on appropriate outputs.
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What is the advantage of choosing a voltage sensing device over a current sensing device for an analog input? - Answer: >> The voltage sensing device will provide a faster response time Sensor sensitivity - Answer: >> 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 The memory space of a POC can be divided according to_____ and ______memory - Answer: >> Program, data Program files - Answer: >> 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 The datafile portion of memory stores: - Answer: >> Input and output status. Processor status. The status of various bits and numerical data Program scan - Answer: >> 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
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Automatic control processes - Answer: >> Involves maintaining a desired set pointThese operations require some form of feedback What would not be classified as a data file - Answer: >> Status Any device that converts energy from one form to another is called a... - Answer: >> Transducer Programing device - Answer: >> Used to enter the desired probably PLCs were originally designed as replacements for - Answer: >> Relay control panels Field or real-world devices refer to - Answer: >> All devices physically wired to the PLC The output interface module connects to - Answer: >> Load devices such as lamps or solenoids Scan time is the time required to - Answer: >> Execute one cycle of the total program
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The programming device must be connected to the controller to run the program - Answer: >> True programming devices used to enter desired program into the memory of the processor Programmable logic controller's are categorized according to the - Answer: >> Number of I/O points One disadvantage of modular I/O is it's lack of flexibility - Answer: >> 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 Standard programming language used to develop a series of instructions that direct the PLC to execute actions is - Answer: >> Ladder logic One function of a PLC input interface module is to - Answer: >> Except signals from field devices and convert them into signals that can be used by the processor Module inserted into the wrong slot could be damaged - Answer: >> True... He module inserted into the wrong side could be damaged by improper voltage is connected through the wiring
Verified Questions.
Which of the following specifications defines the number of field inputs or outputs that could be connected to a single module? - Answer: >> Points per module Analog modules can be either voltage sensing or current sensing - Answer: >> True Memory elements that store information in a PLC are called bits which refers to binary digits - Answer: >> True an analog signal... - Answer: >> Can have an infinite number of states Typically a word in a PLC is - Answer: >> 16 bits The electrical isolation of an analog I/O module specifies how accurately an analog value can be represented digitally - Answer: >> False... The resolution of an analog I/O module specifies how accurately an analog value can be represented digitally The location of a specific input or output feel device is identified by the processor by means of its function - Answer: >> False... The location of a specific input or output field device is identified by the processor by means of its address
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An analog module: - Answer: >> Uses A/D and D/A converters A push button input field device would most likely be used to provide the signal to an analog input module - Answer: >> False... A pushbutton input field device would most likely be used to provide the signal to a discrete input module A unipolar module can except an input signal ranging from - 5 V to +5 V - Answer: >> False... A unipolar module can except an input signal that varies in the positive direction only The selector switches on our workstations are close when the switch is turned to the right - Answer: >> True What is the identifying number in the model number that established the modules are compatible with the Allen - Bradley SLC - 500 family - Answer: >> 1746 How much memory comes with the processors in the workstations in our lab - Answer: >> 16 K What is the file extension for a RSLogix project - Answer: >> .rss
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An AND gate operates on the same principle as a - Answer: >> Series circuit A single rung of a ladder logic program is arranged with: - Answer: >> Input conditions connected from left to right with the output on the far right 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 - Answer: >> 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 The examine if open instruction: - Answer: >> 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 Each complete horizontal line of a ladder logic program is generally referred to as a rung - Answer: >> True How many program files does the PLC processor automatically open when a project is first created - Answer: >> 3...The processor automatically creates to inaccessible system files and the main ladder routine program file when a project is first created
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The status bit of switches and push buttons connected to a PLC are stored in the: - Answer: >> Input image table file The output energize instruction: - Answer: >> 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 The rung condition and the OTE instruction on that rung or false if no logical continuity path has been established - Answer: >> True A interlock maybe used to prevent an output from turning on before another has turned on - Answer: >> True The output latch instruction - Answer: >> 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 Programmed latching circuits are retentive. This means that if power is interrupted the output will _____ when power is returned - Answer: >> Remain in its original on or off state The programmed latching relay instruction is retentive that is if the relay is latched it will unlatch if power is lost and then restored - Answer: >> False...
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The input image table file is changed to reflect the current status of input devices during the program scan phase of operation - Answer: >> 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 In the RSLogixSoftware, where can you find a visual representation of all folders in the current project? - Answer: >> Project tree A ____ Operates by sending sound waves through a target in measuring the time it takes for the pulses to bounce back - Answer: >> Ultrasonic sensor Capacitor proximity sensors: - Answer: >> Our actuated by both conductive and non-conductive materials The force applied to a strain gauge causes it to bend and change its: - Answer:
Resistance
True The output latch instruction - Answer: >> 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 Programmed latching circuits are retentive. This means that if power is interrupted the output will _____ when power is returned - Answer: >> Remain in its original on or off state The programmed latching relay instruction is retentive that is if the relay is latched it will unlatch if power is lost and then restored - Answer: >> False... ## Verified Questions. The input image table file is changed to reflect the current status of input devices during the program scan phase of operation - Answer: >> 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 In the RSLogixSoftware, where can you find a visual representation of all folders in the current project? - Answer: >> Project tree A ____ Operates by sending sound waves through a target in measuring the time it takes for the pulses to bounce back - Answer: >> Ultrasonic sensor Capacitor proximity sensors: - Answer: >> Our actuated by both conductive and non-conductive materials The force applied to a strain gauge causes it to bend and change its: - Answer: >> Resistance An electromechanical relay uses electromagnetism to operate contacts - Answer: >> True Reed switches are activated by magnetism - Answer: >> True
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Proximity switches usually sense the presence or absence of a target by means of physical contact - Answer: >> True
