Have you asked yourself before: What is a PLC? Ever thought of its features and benefits? This article will give you some information about PLCs.
Features of PLC
PLCs share some of the features of electronic devices used in the industry.
First, programmable logical devices differ from parallel working microcontrollers in their use in the field of automated processes in businesses with industrial bias.
Second, capable program controllers aim to communicate with devices through the advanced input of sensor signals and their output for actuators, unlike computers adapted to make decisions through operator control.
Third, PLCs are distinguished from embedded systems as autonomous products in terms of their self-sufficiency. It separates them from the devices controlled.
Benefits of PLC
In addition, the PLC capable program controller feature facilitates the interaction with the user. This is manifested in the programming process of the PLC itself according to a schematic diagram, according to logical equations, and using a basic algorithmic language.
Using optical-electronic isolation of inputs/outputs from external electrical circuits the device was adapted to operate in adverse industrial conditions. This was made possible by the adaptation of the controller to a wide range of operating conditions.
The advantages of programmable controllers include the integration of programming languages, extensive functionality, operational switching of modular units, real-time operating mode, repair, and integration of software due to the possibility of system integration.
Device selection
When choosing a PLC, focus on its compliance with the technical capabilities of the work and its cost.
A large number of manufacturers are busy releasing these controllers. The list includes domestic and foreign companies. For example, the Russian company “Owen” offers a PLC 150 controller that meets all the necessary specifications. The list includes manufacturers “Elmer”, “Amikon”, “Tecon”, NIL AP, and many more.
Well-known foreign manufacturers are Siemens, Mitsubishi, ABB, Omron, Schneider Electric, etc.
Over time, there has been a trend in the evolution of programmable logic controllers. They lose their overall dimension, the set of functional capabilities expands, the number of compatible networks and interface shells increases, the idea of an “open system” is expanding, programming languages are being standardized, and the price is going down.
The advantageous specific features of program controllers capable of personal computers are preserved in the presence of assignments and technical programming codes.
Principle of operation
The working function of PLC controllers is slightly different from standard devices with microprocessors. The software shell of these logic controllers consists of two parts. Like the computer operating system, the controller software manages the working nodes, integrates the components, and performs internal diagnostics. The PLC system shell stays in the read-only memory of the central microchip and is always ready for operation.
The capable program controller operates in cyclical mode by periodically collecting input information. There are four stages to this cycle:
- Polling input.
- Completion of user-assigned tasks.
- Configuration of output parameters.
- Process of other sub-operations.
Controller classification
Concerning I / O lines, PLC controllers are classified as:
- Nano controllers;
- Microcontrollers;
- Medium controllers;
- Large controllers.
Concerning the location of I / O modules:
- Monoblock
- Modular
- Distribution
Depending on the PLC installation method and design:
- Panel
- To climb inside on a special rail;
- To climb the wall;
- For mounting racks;
- Without accommodation (a board).
Here is a short list of the most prominent international companies in the field of PLC:
- Siemens
- Allen Bradley By Rockwell
- ABB
- Mitsubishi
- Omron
- Delta
- PHOENIX CONTACT
- Automation Direct
- Fuji Electric
- Schneider Electric
- Honeywell
- Panasonic
- OPTO 22
- Cimon
- IDEC
- WAGO
- Yokogawa
- PILZ
- B & R
- Selec
- L&T Electrical and Automation
If you are interested in knowing more about the history of PLC you can visit the MRO electric website.