PLC: Chapter 1 - Introduction to PLCs
Test Questions with Solved Solutions
2026-2027 Edition.
B - Answer When were PLCs first introduced
A. 1990s
B. 1980s
C. 1970s
D. 1960s
hardwired relays - Answer What were used before PLCs were introduced?
D - Answer What company was the first to use PLCs to replace relays and complex control
cabinets?
A. Volkswagon
B. Toyota
C. Volvo
D. General Motors Corporation
Ladder Logic - Answer What language was developed for use in PLCs?
false - Answer True/False - When making changes to a PLC after initially wiring is completed,
you only need to change the wires necessary for your desired function
true - Answer True/False The benefit of a PLC is that no wiring has to be changed to change
the operation of the system
I - Answer Of these, which is/are additional language(s) of a PLC
A. Instruction List
B. Repetitive Function Block
C. Sequential Function Chart
D. Function Block
E. A & B
F. A & C
G. C & D
, H. A, B, C, D
I. A, C, D
CPU - Answer This component runs the user program, evaluates the inputs, and generates
outputs. Considered the brain of the PLC
outputs - Answer When using a PLC - Motors, Drives, Lights, Etc. are examples of either
inputs or outputs?
programming device - Answer What device is used to enter the program into the CPU and
also for troubleshooting and monitoring the program
touch screen - Answer provides an operator with the ability to monitor the process and to
enter and retrieve data from the PLC
true - Answer True/False - The parts of a PLC include: Input module, Output module, CPU,
programming device, and touch screen
inputs - Answer Switches, sensors, and touch panel are examples of what?
Top - Answer With the unit facing you and upright, where are the inputs located on the S7-
1200 CPU module
bottom - Answer With the unit facing you and upright, where are the outputs located on the
S7-1200 CPU module
right - Answer With the unit facing you and upright, where are the I/O lights located on the
S7-1200 CPU module
left - Answer With the unit facing you and upright, where are the Run/Stop, Error, and
Maintenance lights located on the S7-1200 CPU module
scan - Answer The process which the PLC performs repetitively is called what
scan - Answer This process of the CPU includes writing the outputs, reading the inputs,
executing the user program and performing system maintenance or background processing.
Continues as long as the CPU remains in run mode. Generally in milliseconds or less.
Test Questions with Solved Solutions
2026-2027 Edition.
B - Answer When were PLCs first introduced
A. 1990s
B. 1980s
C. 1970s
D. 1960s
hardwired relays - Answer What were used before PLCs were introduced?
D - Answer What company was the first to use PLCs to replace relays and complex control
cabinets?
A. Volkswagon
B. Toyota
C. Volvo
D. General Motors Corporation
Ladder Logic - Answer What language was developed for use in PLCs?
false - Answer True/False - When making changes to a PLC after initially wiring is completed,
you only need to change the wires necessary for your desired function
true - Answer True/False The benefit of a PLC is that no wiring has to be changed to change
the operation of the system
I - Answer Of these, which is/are additional language(s) of a PLC
A. Instruction List
B. Repetitive Function Block
C. Sequential Function Chart
D. Function Block
E. A & B
F. A & C
G. C & D
, H. A, B, C, D
I. A, C, D
CPU - Answer This component runs the user program, evaluates the inputs, and generates
outputs. Considered the brain of the PLC
outputs - Answer When using a PLC - Motors, Drives, Lights, Etc. are examples of either
inputs or outputs?
programming device - Answer What device is used to enter the program into the CPU and
also for troubleshooting and monitoring the program
touch screen - Answer provides an operator with the ability to monitor the process and to
enter and retrieve data from the PLC
true - Answer True/False - The parts of a PLC include: Input module, Output module, CPU,
programming device, and touch screen
inputs - Answer Switches, sensors, and touch panel are examples of what?
Top - Answer With the unit facing you and upright, where are the inputs located on the S7-
1200 CPU module
bottom - Answer With the unit facing you and upright, where are the outputs located on the
S7-1200 CPU module
right - Answer With the unit facing you and upright, where are the I/O lights located on the
S7-1200 CPU module
left - Answer With the unit facing you and upright, where are the Run/Stop, Error, and
Maintenance lights located on the S7-1200 CPU module
scan - Answer The process which the PLC performs repetitively is called what
scan - Answer This process of the CPU includes writing the outputs, reading the inputs,
executing the user program and performing system maintenance or background processing.
Continues as long as the CPU remains in run mode. Generally in milliseconds or less.
