PLC TEST 1 QUESTIONS AND ANSWERS
Define a PLC - Answers- Industrial grade computer capable of being programmed to
perform control functions.
Advantages of a PLC over relay logic - Answers- Eliminates most hardwiring. Easy to
use and fast.
Programming Device - Answers- Used to enter the desired program into the memory
CPU - Answers- The Brain; Controls the PLC
I/O System - Answers- Forms the interface to connect field devices to the controller
Power Supply - Answers- Supplies DC power to other modules
Function of an output interface module - Answers- Control external devices
Standard PLC programming language - Answers- Ladder Logic
What does the backplane do? - Answers- Allow modules to be plugged in
Function of an optical isolator - Answers- Separates two circuits using an optical
coupler.
What does the discrete output module recognize? - Answers- Binary on and off signals
PLC keyswitch positions - Answers- Run, Remote, Program
Why does the digital system work so well with computer circuits? - Answers- 0=no
signal 1=signal
What does LSB mean? - Answers- Least Significant Bit
What does MSB mean? - Answers- Most Significant Bit
What is a bit? - Answers- Binary digit, smallest unit in the binary numbering system
What is a byte? - Answers- A group of adjacent bits
What is a word? - Answers- Number of bits treated as a unit
How many bits are there per byte? - Answers- 8
Base of Binary - Answers- 2
, Base of Decimal - Answers- 10
Base of Octal - Answers- 8
Base of Hexadecimal - Answers- 16
ASCII Code - Answers- American Standard Code for Information Interchange
What is The Binary Principle? - Answers- 0=off 1=on
What is a Logic Gate? - Answers- Circuit with several inputs and one output
Name 3 field devices - Answers- Thumbwheel Switch, BCD Output Module, High
Speed Counter Module
When does the programming device need to be connected to the PLC? - Answers-
Troubleshooting and Uploading a Program
PLC Scan Cycle - Answers- Start, Input scan, Program Scan, Output Scan, House
keeping.
Discrete Inputs - Answers- 0/1 on/off
What do analog inputs represent? - Answers- Physical Quantities
How many devices do analog input modules input channels usually allow to be interface
to the PLC? - Answers- 4, 8, 16
What does BCD mean? - Answers- Binary Coded Decimal System
How many bits does a BCD use to represent each decimal digit? - Answers- 4
What is an example of an input device that uses BCD? - Answers- Thumbwheel Switch
PLCs were originally designed as replacements for - Answers- Relay control panels
Field or real-world devices refer to - Answers- All devices physically wired to the PLC
The output interface module connects to - Answers- Load devices such as lamps or
solenoids
Scan time is the time required to - Answers- Execute one cycle of the total program
The programming device must be connected to the controller to run the program -
Answers- True programming devices used to enter desired program into the memory of
the processor
Define a PLC - Answers- Industrial grade computer capable of being programmed to
perform control functions.
Advantages of a PLC over relay logic - Answers- Eliminates most hardwiring. Easy to
use and fast.
Programming Device - Answers- Used to enter the desired program into the memory
CPU - Answers- The Brain; Controls the PLC
I/O System - Answers- Forms the interface to connect field devices to the controller
Power Supply - Answers- Supplies DC power to other modules
Function of an output interface module - Answers- Control external devices
Standard PLC programming language - Answers- Ladder Logic
What does the backplane do? - Answers- Allow modules to be plugged in
Function of an optical isolator - Answers- Separates two circuits using an optical
coupler.
What does the discrete output module recognize? - Answers- Binary on and off signals
PLC keyswitch positions - Answers- Run, Remote, Program
Why does the digital system work so well with computer circuits? - Answers- 0=no
signal 1=signal
What does LSB mean? - Answers- Least Significant Bit
What does MSB mean? - Answers- Most Significant Bit
What is a bit? - Answers- Binary digit, smallest unit in the binary numbering system
What is a byte? - Answers- A group of adjacent bits
What is a word? - Answers- Number of bits treated as a unit
How many bits are there per byte? - Answers- 8
Base of Binary - Answers- 2
, Base of Decimal - Answers- 10
Base of Octal - Answers- 8
Base of Hexadecimal - Answers- 16
ASCII Code - Answers- American Standard Code for Information Interchange
What is The Binary Principle? - Answers- 0=off 1=on
What is a Logic Gate? - Answers- Circuit with several inputs and one output
Name 3 field devices - Answers- Thumbwheel Switch, BCD Output Module, High
Speed Counter Module
When does the programming device need to be connected to the PLC? - Answers-
Troubleshooting and Uploading a Program
PLC Scan Cycle - Answers- Start, Input scan, Program Scan, Output Scan, House
keeping.
Discrete Inputs - Answers- 0/1 on/off
What do analog inputs represent? - Answers- Physical Quantities
How many devices do analog input modules input channels usually allow to be interface
to the PLC? - Answers- 4, 8, 16
What does BCD mean? - Answers- Binary Coded Decimal System
How many bits does a BCD use to represent each decimal digit? - Answers- 4
What is an example of an input device that uses BCD? - Answers- Thumbwheel Switch
PLCs were originally designed as replacements for - Answers- Relay control panels
Field or real-world devices refer to - Answers- All devices physically wired to the PLC
The output interface module connects to - Answers- Load devices such as lamps or
solenoids
Scan time is the time required to - Answers- Execute one cycle of the total program
The programming device must be connected to the controller to run the program -
Answers- True programming devices used to enter desired program into the memory of
the processor
