Title: Module 3 Test
Course: Open EIC225 Programmable Controllers > Section: MODULE 3: Fundamentals of Logic

Q: A gate is a device that:
- allows current flow in one direction only.
- changes alternating current to direct current.
- performs a logical decision based on its inputs.
- performs a logical decision based on its outputs.
A: performs a logical decision based on its inputs.

Q: All gates are devices that have one input with which they perform logic decisions and produce a result at one or more of their outputs.
- True
- False
A: False

Q: All inputs to a NOR gate must be 1 to produce a 1 output.
- True
- False
A: False

Q: An AND gate operates on the same principle as:
- a series circuit.
- a parallel circuit.
- a series-parallel circuit.
- none of these.
A: a series circuit.

Q: A NOR gate is:
- an AND gate with an inverter connected to the output.
- an OR gate with an inverter connected to the output.
- equivalent to a series circuit.
- equivalent to a parallel circuit.
A: an OR gate with an inverter connected to the output.

Q: A NOT function is used when a logic 1 must ________ some device.
- activate
- deactivate
- switch
- light
A: deactivate

Q: A single rung of a ladder logic program is arranged with:
- input conditions connected from left to right, with the output at the far right.
- input conditions connected from right to left, with the output at the far left.
- the output in the center and the input conditions to the left and right of it.
- all input conditions in parallel and all output conditions in series.
A: input conditions connected from left to right, with the output at the far right.

Q: A two input OR function, expressed as a Boolean equation, would be Y= AB.
- True
- False
A: False

Q: Hardwired logic refers to logic control functions determined by the way devices are interconnected.
- True
- False
A: True

Q: If you want to know when one or both matching bits in two different words are ON, you would use the logic instruction.
- AND
- XOR
- OR
- NOT
A: OR

Q: In conventional logic circuits, binary 1 represents:
- the presence of a signal.
- the occurrence of some event.
- a high voltage level.
- all of these.
A: all of these.

Q: Inverting the output of an OR gate will result in creating a NOR gate.
- True
- False
A: True

Q: Ladder logic is a graphical representation of a user program.
- True
- False
A: True

Q: Normally, a binary 1 represents the presence of a signal, while a binary 0 represents the absence of a signal.
- True
- False
A: True

Q: Only one input to an OR gate must be 1 to produce a 1 output.
- True
- False
A: True

Q: On some PLCs, only one output is allowed per ladder logic rung.
- True
- False
A: True

Q: Programmable control is based on logic functions that are programmable and easily changed.
- True
- False
A: True

Q: The AND function, implemented using switches, will mean switches connected in parallel.
- True
- False
A: False

Q: The basic rule for an OR gate is:
- if one or more inputs are 1, the output is 1.
- if one or more inputs are 1, output is 0.
- if one or more inputs are 0, the output is 1.
- both b and c.
A: if one or more inputs are 1, the output is 1.

Q: The basic rule for an XOR function is:
- if one or the other, but not both, inputs are 1, the output is 1.
- if one or more inputs are 1, the output is 1.
- if one or more inputs are 1, the output is 0.
- if one or more inputs are 0, the output is 1.
A: if one or the other, but not both, inputs are 1, the output is 1.

Q: The binary concept makes use of the fact that certain informal:
- can exist in one of two possible states.
- can be broken down into smaller units for easier analysis.
- can be divided into two or more categories.
- can be divided into two, or multiples of two, categories.
A: can exist in one of two possible states.

Q: The Boolean equation for the logic symbol is:
- Y= A + B
- Y= AB
- Y= A • B
- either b or c.
A: Y= A + B

Q: The Boolean equation for the logic symbol is:
- Y= A+B+C
- Y = ABC
- Y= (AB)+C
- Y = (A –B)C
A: Y = ABC

Q: The Boolean equation for the logic symbol is:
- A = Y
- A=B
A: (a choice with no text)

Q: The Boolean expression for the logic circuit drawn is:
- Y = ABC
- Y=A+B+C
- Y = (A + B)C
- Y=AB+C
A: Y=AB+C

Q: The Boolean expression for the logic circuit drawn is:
- Y = (A B)(CD)
- Y= ABC + D
A: (a choice with no text)

Q: The Boolean expression for the logic circuit drawn is:
A: (a choice with no text)

Q: The logic symbol drawn is that of the:
- AND function.
- OR function.
- NOT function.
- NOR function.
A: AND function.

Q: The logic symbol drawn is that of the:
- AND function.
- OR function.
- NOR function.
- NAND function.
A: NAND function.

Q: The logic symbol shown is that of the:
- AND function.
- OR function.
- NOT function.
- NAND function.
A: OR function.

Q: The OR function, implemented using contacts, requires contacts connected in:
- series
- parallel
- series/parallel
- parallel/series
A: parallel

Q: The truth table for the logic symbol is:
- (a)
- (b)
- (c)
- (d)
A: (b)

Q: Which logic circuit represents the Boolean expression Y = A(BC+D)?
- (a)
- (b)
- (c)
- (d)
A: (a)

Q: Which logic circuit represents the Boolean expression
- (a)
- (b)
- (c)
- (d)
A: (b)

Q: Which of the hardwired relay schematics is being implemented by the PLC program shown?
- (a)
- (b)
- (c)
- (d)
A: (b)

Q: According to the data stored in the word corresponding to the outputs, PL1 would be ____, and PL2 would be ___ respectively.
- on, on
- off, off
- on, off
- off, on
A: off, on

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

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

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

Q: A(n) _____ scan pattern examines instructions rung by rung.
- horizontal
- vertical
- input
- output
A: horizontal

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

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

Q: Branch input instructions are used to create a:
- series path of input instructions.
- parallel path of input instructions.
- serial connection of input modules.
- parallel connection of input modules.
A: parallel path of input instructions.

Q: Each complete horizontal line of a ladder diagram is generally referred to as a(n):
- rung.
- branch.
- input.
- output.
A: rung.

Q: For the input module shown, the data stored in the word corresponding to the open switch would be ___ and that for the closed switch would be ___ respectively.
- 1, 1
- 0, 1
- 0, 0
- 1, 0
A: 1, 0

Q: For the matrix limitation diagram shown, maximum number of series contacts allowed per rung is
- one.
- four.
- five.
- limited only by the memory size.
A: five.

Q: For the matrix limitation diagram shown, maximum number of outputs allowed per rung is:
- one.
- four.
- five.
- limited only by the memory size.
A: one.

Q: For the program shown, instruction B represents an:
- Examine If Closed instruction.
- Examine If Open instruction.
- Output Energize instruction.
- Input Energize instruction.
A: Examine If Open instruction.

Q: For the program shown, instruction, Y represents an:
- Examine If Closed instruction.
- Examine If Open instruction.
- Output Energize instruction.
- Input Energize instruction.
A: Output Energize instruction.

Q: For the scan process shown, the input data is provided by the:
- ladder program.
- output module.
- input module.
- all of these.
A: ladder program.

Q: If a PLC has a total scan time of 10 ms and has to monitor a signal that _____ then the controller may not detect this change.
- changes state once in 20 ms
- is fast
- is constantly changing
- changes state twice in 5 ms
A: is constantly changing

Q: In diagram shown, the nested contact is contact:
- B.
- C.
- D.
- E.
A: E.

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

Q: Parallel connections of ladder logic are typically called:
- rungs.
- networks.
- coils.
- branches.
A: branches.

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

Q: The address for the point on the I/O module shown would be:
- I:6/1
- I:1/6
- O:6/1
- O:1/6
A: I:1/6

Q: The address I:1/3 identifies an input module residing in slot ___ of the PLC chassis.
- zero
- one
- two
- three
A: one

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

Q: The address O:3/7 would be found on terminal ____ of an output module residing in slot ___ of the PLC chassis.
- 3, 7
- 7, 3
- 4, 7
- 7, 4
A: 7, 3

Q: The bit status condition of the input device shown connected to address I:2/8 must be ___ to turn on output address O:3/6.
- 0
- 1
- normally open
- normally closed
A: 0

Q: The Boolean equation for the logic represented in the ladder logic program shown can be expressed as:
- Y = (A) + (CD) + (BC)
- Y= A + B + (CD)
- Y = (AB) + (CD)
- Y = A(BCD)
A: Y = (A) + (CD) + (BC)

Q: The Boolean equation for the logic represented in the ladder diagram can be expressed as:
- Y = (AB) + (ACD) + (DE)
- Y = (AB) + (ACD) + (DE) + (BCE)
- Y = (AB) + (AC) + (AD) + (ED)
- Y= (AB) + (CD) + E
A: Y = (AB) + (ACD) + (DE) + (BCE)

Q: The Examine If Closed instruction:
- is also known as the Examine-On instruction.
- is also known as the XIC instruction.
- looks and operates like a normally open relay contact.
- all of these.
A: is also known as the Examine-On instruction.

Q: The Examine If Open instruction:
- is also known as the Examine-Off instruction.
- is also known as the XIO instruction.
- looks and operates like a normally closed relay contact.
- all of these.
A: all of these.

Q: The highlighted rungs in the program rung shown indicate:
- the instruction is true.
- the instruction is false.
- the instruction does not have logic continuity.
- both b and c.
A: both b and c.

Q: The ____ instructions always interpret a 1 status as true and a 0 status as false.
- XIC
- XIO
- contact
- all of these
A: XIC

Q: The last element to be entered on a ladder rung is a(n):
- coil.
- contact.
- XIC instruction.
- XIO instruction.
A: coil.

Q: The memory organization of a PLC can be divided into two broad categories:
- Input and output image files
- Timer and counter files
- Program and data files
- Control and integer
A: Program and data files

Q: The most likely module address for LS1 is:
- LS1 I2
- LS1 O2
- I:2/2
- O:2/2
A: I:2/2

Q: The most likely module address for PL1 is:
- I:3/6
- I:6/3
- O:3/6
- O:6/3
A: O:3/6

Q: The Output Energize instruction:
- is also known as the OTE instruction.
- signals the PLC to energize or deenergize the output.
- looks and operates like a relay coil.
- all of these.
A: all of these.

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

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

Q: The _________ will account for most of the total memory of a given PLC system.
- input image table file
- output image table file
- user program
- internal operating instructions
A: user program

Q: When a program rung consists of an output instruction only, the output would then be:
- continuously ON.
- continuously OFF.
- shorted.
- both a and c.
A: continuously ON.

Q: When the PLC is required to operate the user program without energizing any outputs, it is placed in the ___ mode.
- RUN
- CLEAR MEMORY
- PROGRAM
- TEST
A: TEST

Q: When using an XIC instruction, the reference address could be:
- a bit from an input device.
- a bit from an output device.
- a bit from an internal relay.
- any of these.
A: any of these.