PLC 1 Flashcards
also referred to as
programmable controllers, are in the computer family.
Programmable Logic Controllers(PLCs)
monitors
inputs, makes decisions based on its program, and controls
outputs to automate a process or machine.
Programmable Logic Controllers(PLCs)
Parts of PLC
input modules or points, a Central Processing
Unit (CPU), and output modules or points.
input modules or points, a Central Processing
Unit (CPU), and output modules or points.
PLC parts
accepts a
variety of digital or analog signals from various field devices
(sensors) and converts them into a logic signal that can be used
by the CPU.
INPUT or INPUT modules or points
CPU
makes decisions and executes control
instructions based on program instructions in memory.
makes decisions and executes control
instructions based on program instructions in memory.
CPU
NPUT or INPUT modules or points
accepts a
variety of digital or analog signals from various field devices
(sensors) and converts them into a logic signal that can be used
by the CPU.
convert control instructions from the CPU into a digital
or analog signal that can be used to control various field devices
(actuators).
Output
modules
Output
modules
convert control instructions from the CPU into a digital
or analog signal that can be used to control various field devices
(actuators).
is used to input the desired
instructions. These instructions determine what the PLC will do
for a specific input.
Programming Device
Programming Device
is used to input the desired
instructions. These instructions determine what the PLC will do
for a specific input.
allows process
information to be displayed and new control parameters to be
entered.
An operator interface device
An operator interface device
allows process
information to be displayed and new control parameters to be
entered.
Prior to PLCs, what are the devices used to control the task done by PLC
RELAY controls or Contactor
RELAY controls or Contactor
devices used to control the task prior to PLCs
Hard-wiring
Method used for automating Inputs and outputs of a system through relay or contactor.Circuit diagrams had to be designed, electrical
components specified and installed, and wiring lists created.
Electricians would then wire the components necessary to
perform a specific task. If an error was made the wires had
to be reconnected correctly. A change in function or system
expansion required extensive component changes and rewiring.
Method used for automating Inputs and outputs of a system through relay or contactor.Circuit diagrams had to be designed, electrical
components specified and installed, and wiring lists created.
Electricians would then wire the components necessary to
perform a specific task. If an error was made the wires had
to be reconnected correctly. A change in function or system
expansion required extensive component changes and rewiring.
Hard Wiring
advantages of PLCs
Smaller physical size than hard-wire solutions.
* Easier and faster to make changes.
* PLCs have integrated diagnostics and override functions.
* Diagnostics are centrally available.
* Applications can be immediately documented.
* Applications can be duplicated faster and less expensively.
Samples of application of PLCs
smaller, stand-alone applications such as elevators, car washes,
or mixing machines. It can also be used on more complex
industrial applications such as bottling and packaging machines.
Characteristics of number systems
digits, base, weight.
information in the form of
On or Off conditions (1 or 0),
Binary digits
digits in terms of Decimal
0,1,2,3,4,5,6,7,8,9
Base or Radix in terms of Decimal
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