Programmable Logic Controller (PLC) Practice Test

These questions are part of the practice quiz. Start practicing

• What does the datafile portion of memory store?
• On a rung, the OTE will energize the output only if which of the following is true?
• What kind of interface does a programming device usually use?
• Which PLC instruction sets an output bit to one when its input becomes true and retains its state after the input loses continuity or power?
• Which components make up the two fundamental memory divisions mentioned for PLC memory?
• Which statement best describes the effect of modular I/O design on flexibility?
• Proximity switches usually sense the presence of a target without physical contact.
• What is the completion of one PLC operating cycle commonly called?
• Which statement about discrete I/O modules being bit oriented is true?
• Resolution is defined as:
• Field or real-world devices refer to
• Typically a word in a PLC is 16 bits.
• The output interface module connects to
• Analog I/O modules can be configured to sense either voltage or current.
• When verifying a program before loading it, which action is appropriate?
• A process that requires operations to be performed without regard to the order is described as a:
• In PLC terminology, what does the term 'address' refer to?
• How much memory comes with the processors in the workstations in our lab?
• What is the advantage of choosing a current sensing device over a voltage sensing device for an analog input?
• Module inserted into the wrong slot could be damaged
• In a PLC system, what is a primary role of the input interface module?
• The term that describes inputs and outputs that can have an infinite number of states is:
• How does the processor identify the location of a specific input or output field device?
• Which PLC component receives signals from field devices and provides binary state to the CPU?
• A signal which can vary continuously is called...
• In order to read I/O for a project what must you do first?
• Which description best defines sensors?
• ScanTime is defined as the time required for one full cycle of a PLC.
• What is the purpose of an interlock in ladder logic?
• Programmed latching circuits are retentive. If power is interrupted, the output will do what when power is returned?
• Capacitor proximity sensors are actuated by which materials?
• When is the XIO instruction true with respect to a physical input terminal?
• Ladder logic is the standard programming language used to develop a series of instructions that direct the PLC to execute actions
• PLCs were originally designed as replacements for
• Which statement best describes a programming device's function?
• Field devices are identified by the processor by means of their addresses.
• A discrete input module handles digital on/off signals.
• Hardwired logic is programmable and easily changed.
• The selector switches on our workstations are closed when the switch is turned to the right.
• Where are the status bits for input devices stored in the PLC file structure?
• Which term specifies a circuit that maintains current flow after the initiating momentary switch is released?
• Memory elements that store information in a PLC are called what?
• The memory space of a PLC can be divided according to which two types?
• An internal output is addressed to a bit in the B3 file rather than an address in the output image table. This statement is:
• The advantage of using current-based sensing devices is:
• Which device converts electrical energy into mechanical motion using an electromagnet?
• A unipolar module can accept an input signal that varies in the positive direction only.
• If you want to know when one or both matching bits in two different words are on you would use the logic instruction
• Analog data is stored in memory as a word, with addressing examples such as I:2.0 or O:2.0. What does this imply about the data type?
• Program files in the processor memory are identified by file numbers in what range, and which files are automatically created?
• The PLC Run Mode of operation is selected to execute the user program. Which option corresponds to this mode?
• What are the primary functions of the CPU in a PLC?
• Modular I/O systems consist of divided compartments into which separate models can be plugged. This design feature
• The examine if open instruction is also known as which term?
• The force applied to a strain gauge causes it to bend and change its
• Interlox is a PLC programming technique used primarily for which purpose?
• The identifying number in the model number that established the modules are compatible with the Allen-Bradley SLC-500 family is 1746.
• One function of a PLC input interface module is to
• What is a typical limitation of a programming device in runtime operation?
• The XIO instruction evaluates to true when the addressed memory bit is what value?
• What term describes the time required for one full cycle in a PLC?
• What term describes a method of maintaining current flow after a momentary switch has been pressed and released?
• The XIO instruction looks like which type of contact?
• Programmable logic controllers are categorized according to
• Which statement best describes the PLC input interface?
• Which statement about the PLC input interface is correct?
• Is offline programming with a programming device possible?
• The OTE instruction is functionally described as which component?
• What components are contained in an analog I/O module?
• A programmed latching relay instruction is retentive. If the relay is latched and power is lost and then restored, the relay will:
• What is a PLC program?
• Which PLC component connects directly to field devices such as pilot lights, motor starters, and solenoids?
• Which statement about the Output Latch (OTL) is true?
• What power supply is connected to the normally open push buttons on the workstation?
• Current source modules are characterized by which statement?
• Which phase updates the input image table to reflect the status of input devices?
• Current sink modules are characterized by which statement?
• Which statement is not a function of the CPU?
• The Allen-Bradley SLC-500 address I:2/4 refers to a
• Which item would not be classified as a data file in PLC terminology?
• What term describes a label or number indicating where information is located in a PLC's memory?
• Which control process requires feedback to maintain a desired set point?
• A bipolar input module can accept signals that:
• An analog module uses A/D and D/A converters.
• The XIO instruction is commonly abbreviated for which phrase?
• Electrical isolation of an analog I/O module specifies how accurately an analog value can be represented digitally.
• Which statement describes an electromechanical relay?
• The analog output signal is varied under the control of the PLC program and can be used to control what?
• One function of a PLC input interface module is to
• How many program files does the PLC processor automatically open when a project is first created?
• Which component is described as a physical hardware assembly that houses devices such as I/O modules, processor models, and power supplies?
• What is the primary purpose of a programming device in PLC systems?
• The output interface module connects to load devices such as lamps or solenoids
• A pushbutton input field device would most likely be used to provide the signal to a discrete input module.
• The programming device must be connected to the controller to run the program
• What is typically the first step when programming a PLC with a programming device?
• Which component is typically wired to 24 VAC in the workstation input circuit?
• A push button input field device would most likely be used to provide the signal to an analog input module.
• What is a PLC?
• What is the file extension for a RSLogix project?
• Which statement about voltage-based versus current-based sensors is true according to the material?
• What is an important security consideration when using a programming device?
• For the AC discrete input module circuit schematic, what is the purpose of the optical isolator?
• The location of a specific input or output field device is identified by the processor by means of its address.
• An unipolar input module can accept an input signal that varies in the:
• The Run mode is used to execute the user program. Which option best describes this function?
• What value is stored in the memory location when there is no voltage at the terminal?
• Which functions are performed by the PLC CPU?
• What does an analog output module do in a PLC system?
• Which of the following is true about the logical rack's I/O point counts?
• An analog signal can have an infinite number of states.
• Discrete I/O are characterized by which statement?
• ______ Relays are used where it is necessary for the contact state to stay open or closed even if the coil is energized only momentarily.
• Scan time is the time required to
• Discrete I/O modules can be classified as
• Which statement best describes the output energize instruction (OTE)?
• An analog input module converts analog signals to digital values using an A/D converter.
• A control process that involves maintaining a desired set point and requires some feedback is called:
• Sensor sensitivity describes what?
• Which of the following best describes when an OR operation outputs a high in digital logic?
• In PLC terminology, an internal output does not directly control an external field device. This statement is:
• Which statement about normally intensified rungs on a PLC display is correct?
• The term that describes inputs and outputs that have only two states: on and off is:
• Which type of relay maintains its contact state after the control coil is energized only momentarily?
• There is no difference between a relay schematic and a ladder logic program.
• After programming, what is a good practice?
• Which statement best describes sensors?
• Standard programming language used to develop a series of instructions that direct the PLC to execute actions is
• In SLC-500 addressing, what do the designators I and O indicate?
• Which statement best describes the relationship between relay schematics and ladder logic program symbols?
• The logical rack is an addressable unit consisting of how many input and output points?
• Which term best describes a device that converts energy forms and is commonly used in measurement and control systems?
• Before disconnecting a programming device, which precaution is recommended?
• Which component is responsible for converting between analog and digital signals within an analog I/O module?
• What is a complete horizontal line in a ladder logic program commonly referred to as?
• What occurs during each program scan cycle?
• Reed switches are activated by magnetism.
• Which device is designed to control output devices based on input signals and a user-developed program?
• Which PLC component is directly responsible for turning field devices on or off?
• Which capability is commonly associated with a programming device?
• How can you view the contents of PLC data files in the programming software?
• The advantage of using a sensor that uses voltage is:
• Proximity switches usually sense the presence or absence of a target by means of physical contact.
• How are analog inputs and outputs addressed in the PLC?
• Which type of input is designed to handle gradually varying signals rather than just on/off?
• The input image table file is changed to reflect the current status of input devices during the program scan phase of operation. True or False?
• In general terms, what is a Transducer?
• A new PLC project automatically creates three program files: two inaccessible system files and the main ladder routine program file. This statement is:
• What is the memory size of the processors in the lab workstations?
• Which device is activated by magnetism?
• The Examine If Closed instruction requires how much memory in a program file?
• Which statement best describes the PLC output interface?
• Where is the main ladder routine program file located in a newly created RSLogix project?
• In RSLogixSoftware, where can you find a visual representation of all folders in the current project?
• Which term describes a wiring or programming technique used for sequencing and safety by ensuring outputs turn on or off under specified conditions?
• In a ladder logic rung, where is the output located relative to the input conditions?
• For the AC discrete input module circuit schematic, what is the purpose of the filter section?
• Which step helps ensure data integrity when programming a PLC?
• Status indicators on an output module indicate which of the following?
• A _____ is an actuator that could be controlled by discrete output from a PLC.
• Which circuit is specifically designed to maintain current flow after a momentary activation to keep a circuit energized?
• The Allen-Bradley SLC-500 address O:3/0 refers to which of the following?
• Which statement correctly pairs the term with its state characteristic?
• One disadvantage of modular I/O is its lack of flexibility
• How should multiple program versions be managed with a programming device?
• How does a programming device differ from an operator console?
• An AND gate operates on the same principle as a
• Which specification defines the number of field inputs or outputs that could be connected to a single module?
• And or gate operates on the same principle as a:
• A process that demands operations to be performed in a specific order is described as a:
• Which action is commonly performed by a programming device?
• Analog modules can be either voltage sensing or current sensing.
• What is the correct file extension for an RSLogix project?
• What device operates by sending sound waves through a target to measure the time for the pulses to bounce back?
• How many program files are automatically opened by the PLC processor when a new project is created?
• Which statement best describes the PLC chassis?
• Which component provides isolation between high voltage and the PLC logic in input circuits?
• What is the main advantage of using a voltage sensing device over a current sensing device for analog inputs?