The Advantages and Disadvantages of PLC (Programmable Logic Controller)
At first, any production engine is electronically controlled, requiring each control, for example, 12 machine requires 12 controller. Now by using the model of the PLC can control any of the 12 machines. Each machine is controlled by its own respective programs.
By using the type of relay that is connected to the panel, program changes will take time to re-connect panels and equipment. While using the PLC, to make changes to the program, does not require a long time is by way of a change in software. And if the program error occurs, then the error can be directly detected by monitoring its existence directly. The change is very simple, just change its ladder diagram.
PLC is simpler in shape, size, and other devices that support it, so the price can be reached. Current can be purchased the following PLC timers, counters, and analog inputs in a single CPU package. PLC easy to get, and now many in the market with different brands and types.
PLC has a number of contacts for each coil are many available. For example, the panel that connects the relay has 5 contacts and all use while on the design changes needed 4 more contact means required the addition of a single relay again. This means that the time required to perform the installation. By using PLC, typing required just to make contact again 4 pieces. Hundreds of contacts can be used from a single relay, if the memory on the computer is still possible.
The series of PLC programs can be tested first, tested, examined and modified at the office or laboratory, so the time efficiency can be achieved. To test the PLC program does not have to be installed first to the instrument to be executed, but can be seen directly in the PLC CPU or seen in the supporting software.
Operation of the circuit can be seen during the PLC operated directly via the CRT screen. If there are errors or mistakes that other operations can be immediately known. Logic path will light up on the screen so that repairs can be done quickly through visual observation. Even some PLC can provide an error message if it occurs.
Operating speed of the PLC, exceeds the operating speed than relay at work, which in a few micro-seconds. So as to determine the speed of the output of the tools used.
PLC programs can be done with a ladder diagram by the technician or also use bolean or digital system for the programmers. PLC which is easier and can be simulated in software supporters.
Solid state equipment is generally more resistant than mechanical relays or timers. PLC is able to work in severe environmental conditions, such as shock, dust, high temperatures, and so on.
PLC is one piece of equipment with a delivery time. If the PLC arrives, then all relays, counters, and other components also arrived. If the relay panel design as much as 10 pieces, it would require 10 different supplier delivery time, so if you forgot to order one relay will result in delays in processing a panel.
Print series PLC can be done real soon in part or whole without the need to look at a series of blueprints that are not necessarily up to date, and also do not need to check the wiring to the circuit path.
PLC programs can not be changed by anyone and can be made password. While the regular relay panel allows for changes that are difficult to detect.13. Facilitate change by reprogramming.
PLC can be quickly re-programmed, it is possible to mix the production process, while the other is running production.
Difficult to change the mindset of some of the personnel who have long used the concept of a relay to turn the concept into a computer PLC.
2. Application programs remain
Some applications of the production process is an application that is not going to change forever so the advantages of the PLC to change the program to be useless.
Certain environmental processes such as high heat and vibration, interference with other electrical appliances to make limited use of PLC.
On the use of relay systems, if the resource will be extinguished immediately shut off all circuits and do not automatically work again. PLC will immediately execute processes in the program, but this depends on the program made.5. Operating at a fixed series
If a series of operating have not been changed, such as mechanical drum, cheaper if still using the concept of using a relay of the PLC.