Programmable Logic Control (PLC)

A Programmable Logic Control (PLC) is basically a program associated with equipment and input / output (I / O) in the form of relays (solid state relays). PLC controls the program, so if there is an input device ON, the PLC provides a response to a change in this input. This response is usually a signal to the output terminal. Input devices may include sensors photolistrik, buttons on the panel, divider switch (limit switches), or any equipment that could provide input on the PLC input signals. Meanwhile, output devices, can be a solenoid, the switch that activates the lights, relays, or motors that rotate every equipment that can be driven by the PLC output signal.Initially PLC is a relay-based control system. This system is an integrated strand of which took over the duties of equipment such as relays, timers and counters. PLC actual operations follow a similar operation if the equipment (relays, etc.) are still in place. But it also has the capacity of PLC such as computers and have the flexibility and reliability better than the relay system. But most of the term to describe the symbols and concepts come from computer terms such as AND, OR etc. mnemonic.

In the brain (CPU = Central Processing Unit) can be imagined as a collection of thousands of relays. But that does not mean there are a lot of relays within a very small in size. In the PLC contains a digital electronic circuit that could be used as contact NO and NC relay contact


Advantages compared to conventional PLC control panel
 Systems PLC:
1. Fewer Wiring
2. Spare parts easily
3. Maintenance is relatively easy
4. Simpler tracking system error
5. Relatively low power consumption
6. Image documentation much simpler and easier to understand
7. Modification of the system simpler and faster
 Conventional control panels:
1. Wiring is more complex
2. Spare parts are relatively difficult
3. Maintenance requires a long time
4. Tracking error requires a longer time
5. Relatively high power consumption
6. More pictures Documentation
7. System modifications require a long time
The advantage of using PLC
1. Old workmanship for a new system of shorter redesigned
2. Modification of the system may at no additional cost if there is spare I / O
3. Estimated cost of a new design system more definite
4. Relatively easy to learn
5. Design new systems easy to modify
6. PLC is very broad application
7. Easy in maintenance
8. Very reliable
9. Standardization of the control system easier to implement
10. It's safer for technicians

A PLC configuration
1. Power Supply: This unit serves to provide sunber power in the PLC. This module has a switching power supply
2. CPU (Central Processing Unit): This unit is the brain of the PLC. This is where the program will be processed so that we have control systems designed to work like we want. Omron PLC CPU types vary greatly depending on each type of PLC him.
3. Memory Unit: RAM, EPROM, EEPROM