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#Oplc definition how to
#Oplc definition software

If required by your application, can the PLC handle analog inputs and outputs, or maybe a combination of both analog and discrete inputs and outputs?.

Will the PLC be able to manage the number of inputs and outputs that my application requires?.

#Oplc definition software

What type of software is used to program the PLC?.

Does the system run fast enough to meet my application’s requirements?.

Does the PLC have enough memory to run my user program?.

Will the system be powered by AC or DC voltage?.

Other than cost, you must consider the following when deciding which one will best suit the needs of your application. There are many PLC systems on the market today. What Do I Need To Consider When Choosing A PLC? Instruction List (IL): A low level “assembler like” language that is based on similar instructions list languages found in a wide range of today’s PLCs. It has a language structure (syntax) that strongly resembles PASCAL and supports a wide range of standard functions and operators. Structured Text (ST) – A high level text language that encourages structured programming. FBD is very useful for expressing the interconnection of control system algorithms and logic. Initially programmed with simple contacts that simulated the opening and closing of relays, Ladder Logic programming has been expanded to include such functions as counters, timers, shift registers, and math operations.įunction Block Diagram (FBD) - A graphical language for depicting signal and data flows through re-usable function blocks. Ladder Diagram (LD) Traditional ladder logic is graphical programming language. The following table lists of some of languages that are used to program a PLC. While Ladder Logic is the most commonly used PLC programming language, it is not the only one. What Programming Language Is Used To Program A PLC?

This step includes communications with programming terminals,.

Energizes or de-energize all output devices that are connected to the PLC.

Executes the user created program logic.

Detects the state of all input devices that are connected to the PLC.

These steps continually take place in a repeating loop. There are four basic steps in the operation of all PLCs Input Scan, Program Scan, Output Scan, and Housekeeping.

Perform Housekeeping activities such as Communications, Internal Diagnostics, etc.

Communicate with other devices, which can include I/O Devices, Programming Devices, Networks, and even other PLCs.

This program is stored in "nonvolatile" memory, meaning that the program will not be lost if power is removed

Execute the Control Instructions contained in the User's Programs.

#Oplc definition how to

The Central Processing Unit, the CPU, contains an internal program that tells the PLC how to perform the following functions:

The first commercial successful PLC, the 184, was introduced in 1973 and was designed by Michael Greenberg.

The first PLC, model 084, was invented by Dick Morley in 1969.

The new system drastically increased the functionality of the controls while reducing the cabinet space that housed the logic.

These controllers eliminated the need for rewiring and adding additional hardware for each new configuration of logic.

The first Programmable Logic Controllers were designed and developed by Modicon as a relay re-placer for GM and Landis.

That is, you can mix and match the types of Input and Output devices to best suit your application. However, the biggest benefit in using a PLC is the ability to change and replicate the operation or process while collecting and communicating vital information.Īnother advantage of a PLC system is that it is modular. A PROGRAMMABLE LOGIC CONTROLLER (PLC) is an industrial computer control system that continuously monitors the state of input devices and makes decisions based upon a custom program to control the state of output devices.Īlmost any production line, machine function, or process can be greatly enhanced using this type of control system.