Who invented PLCs?
Many people consider Dick Morley to be the originator of the programmable logic controller (PLC). His contribution to the 1968 development of the first Modicon PLC for General Motors was a pivotal moment for automation and industrial control.
An electronic system created for industrial applications is a programmable controller. In order to govern via inputs and outputs, it implements certain solutions using a programmable memory, such as logic functions, sequence, timing counts, and arithmetic functions.
An essential components of PLC:
- Power module – the Engine, input, and output modules in the rack should be powered.
- Central Processing Unit (CPU) – It carries out logical, mathematical, and sequential procedures.
- Input and output module It both receives field inputs and outputs to field devices. For input and output devices, wiring is present.
- Communication interface module – The interface module is coupled to the I/O modules in a single or several racks.
As the structural core of all PLC systems and servers, the PLC rack or chassis is the most crucial module.
Based on the I/O modules extension facility, there are two different types of PLCs.
- Compact PLCs have an I/O module with a fixed capacity.
- With a modular PLC, an I/O module’s capacity is expandable; it does not have a set value.
To better grasp the distinction between compact PLC and modular PLC, let’s first define compact & modular PLC.
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Compact PLC
Because all of its components are built into the device, a compact PLC is a controller whose basic configuration cannot be changed over time.
Processor, power supply, input, and output modules are all included in one package with integrated systems. When the compact PLC is utilized in small applications, the CPU, I/O, battery, memory, and occasionally even the power supply, cabling, and software, are all incorporated into a single machine.
The standard configuration includes a predetermined number of digital IOs (no more than 30), one or two communication channels (for configuring the PLC and attaching the field buses), and an HMI.
A high-speed counter input and one or two analogue IOs may also be present. The modules that can be linked are (further) enhanced in order to increase the number of IOs of a certain small PLC. They are contained in a container that resembles the PLC itself. Compact-type PLCs are employed in every industry as relay replacements.
Modular PLC
The term “modular” refers to a form of PLC that allows for various expansions of the PLC system using modules. Larger applications benefit greatly from using this kind of PLC. The motherboard, CPU, RAM, input module, and output module are just a few examples of the modules that make it up (or mixed). Depending on the requirements, the inputs and outputs will either be digital or analogue.
Given that it may accommodate hundreds of inputs and outputs, it is the most sophisticated sort of PLC. The preceding ones with the power supply, Processor, input and output modules are also present. It is the most potent variety of PLC when compared to compact PLCs.
On a DIN rail or on a rail with Programmable Logic Controllers (PLC) with the CPU through a bus system, the CPU, Power supply, Communication module, and other modules are often in different packages.
The modular PLC will typically have a finite number of module slots, but this may usually be extended. Modular PLCs can also support more programme, store more data, employ a greater number of inputs and outputs, and function in multitasking mode. They are typically used for motorization, control, regulation, positioning, data processing, manipulation, communication, positioning, and other purposes.
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