Michigan PLC Programmer Exam,
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is a primary function of a Programmable
Logic Controller (PLC)?
a) Measure analog signals only
b) Store and retrieve large databases
c) Control industrial processes automatically
d) Perform complex scientific computations
Rationale: PLCs are designed primarily to control industrial machinery
and processes by executing logic based on input conditions, making c
correct.
2. Which type of memory in a PLC is typically non-volatile and
retains programs after power loss?
a) RAM
b) EEPROM
c) Cache memory
d) ROM
Rationale: EEPROM (Electrically Erasable Programmable Read-Only
Memory) retains stored programs even when power is lost, unlike
RAM, which is volatile.
, 3. Ladder Logic programming in PLCs is most closely based on:
a) Structured text
b) Functional block diagrams
c) Relay logic schematics
d) Sequential function charts
Rationale: Ladder Logic visually resembles traditional relay logic
diagrams, making c the correct answer.
4. In a PLC, what is the function of an input module?
a) Process data and execute instructions
b) Receive signals from sensors and devices
c) Output control signals to actuators
d) Store the program logic
Rationale: Input modules read signals from sensors or switches and
communicate them to the CPU.
5. A PLC scan cycle consists of which of the following steps?
a) Only executing output instructions
b) Reading inputs, executing logic, updating outputs
c) Reading inputs and updating outputs without executing logic
d) Executing logic only
Rationale: The PLC scan cycle follows the sequence of reading inputs,
executing the program logic, and updating outputs.
6. Which PLC programming language is text-based and similar to
high-level languages?
a) Ladder Diagram (LD)
b) Function Block Diagram (FBD)
c) Structured Text (ST)
d) Sequential Function Chart (SFC)
, Rationale: Structured Text is a high-level, text-based programming
language used in PLCs for complex logic.
7. What is the main purpose of a “watchdog timer” in a PLC?
a) Backup memory storage
b) Execute specific instructions faster
c) Detect and recover from CPU malfunctions
d) Monitor network traffic
Rationale: A watchdog timer ensures the CPU is functioning properly
and resets it if the scan cycle fails or hangs.
8. In PLC terminology, a “bit” is primarily used to represent:
a) A numeric value
b) A binary condition (ON or OFF)
c) An analog signal
d) A memory address
Rationale: PLCs use bits to represent discrete ON/OFF states, such as a
switch being closed or open.
9. Which of the following devices commonly provides analog input
to a PLC?
a) Pushbutton
b) Limit switch
c) Temperature sensor with 4–20 mA output
d) Relay coil
Rationale: Analog devices like 4–20 mA sensors provide varying signals,
which the PLC input module reads as analog values.
10. A normally open (NO) contact in ladder logic closes when:
a) The PLC power is off
b) The corresponding input or output condition is true
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is a primary function of a Programmable
Logic Controller (PLC)?
a) Measure analog signals only
b) Store and retrieve large databases
c) Control industrial processes automatically
d) Perform complex scientific computations
Rationale: PLCs are designed primarily to control industrial machinery
and processes by executing logic based on input conditions, making c
correct.
2. Which type of memory in a PLC is typically non-volatile and
retains programs after power loss?
a) RAM
b) EEPROM
c) Cache memory
d) ROM
Rationale: EEPROM (Electrically Erasable Programmable Read-Only
Memory) retains stored programs even when power is lost, unlike
RAM, which is volatile.
, 3. Ladder Logic programming in PLCs is most closely based on:
a) Structured text
b) Functional block diagrams
c) Relay logic schematics
d) Sequential function charts
Rationale: Ladder Logic visually resembles traditional relay logic
diagrams, making c the correct answer.
4. In a PLC, what is the function of an input module?
a) Process data and execute instructions
b) Receive signals from sensors and devices
c) Output control signals to actuators
d) Store the program logic
Rationale: Input modules read signals from sensors or switches and
communicate them to the CPU.
5. A PLC scan cycle consists of which of the following steps?
a) Only executing output instructions
b) Reading inputs, executing logic, updating outputs
c) Reading inputs and updating outputs without executing logic
d) Executing logic only
Rationale: The PLC scan cycle follows the sequence of reading inputs,
executing the program logic, and updating outputs.
6. Which PLC programming language is text-based and similar to
high-level languages?
a) Ladder Diagram (LD)
b) Function Block Diagram (FBD)
c) Structured Text (ST)
d) Sequential Function Chart (SFC)
, Rationale: Structured Text is a high-level, text-based programming
language used in PLCs for complex logic.
7. What is the main purpose of a “watchdog timer” in a PLC?
a) Backup memory storage
b) Execute specific instructions faster
c) Detect and recover from CPU malfunctions
d) Monitor network traffic
Rationale: A watchdog timer ensures the CPU is functioning properly
and resets it if the scan cycle fails or hangs.
8. In PLC terminology, a “bit” is primarily used to represent:
a) A numeric value
b) A binary condition (ON or OFF)
c) An analog signal
d) A memory address
Rationale: PLCs use bits to represent discrete ON/OFF states, such as a
switch being closed or open.
9. Which of the following devices commonly provides analog input
to a PLC?
a) Pushbutton
b) Limit switch
c) Temperature sensor with 4–20 mA output
d) Relay coil
Rationale: Analog devices like 4–20 mA sensors provide varying signals,
which the PLC input module reads as analog values.
10. A normally open (NO) contact in ladder logic closes when:
a) The PLC power is off
b) The corresponding input or output condition is true
