In industries that exist right now, the presence of PLC is necessary especially to replace the wiring or cabling systems that previously were used in controlling a system. By using the PLC will get many benefits which are as follows:
In the past, each different electronic device controlled by each controller. Suppose ten machines require ten controllers, but now with only one tenth PLC machine can be run with each program.
2. Changes and error correction system easier
If one system will be modified or corrected, the change is only done on the programs contained in computers, in a relatively short time, after that it downloaded to the PLC. If not using a PLC, for example relays the amendments made by altering the wiring cables. This course takes a long time.
3. Number of contacts many
Number of contacts held by the PLC on each coil is more than the contacts held by a relay.
PLC is capable of simplifying a lot of cabling compared to a relay. So the price of a PLC at a price cheaper than some fruit relay capable of doing the wiring for the same amount with a PLC. PLC includes relays, timers, counters, sequencers, and other functions.
5. Operating speed
PLC operation speed is faster than the relay. Speed PLC scan time is determined by its in units of milliseconds.
6. Resistant character test
Solid state devices are more resistant than the relay and test mechanical or electrical timers. PLC is a solid state device that is more resistant test.
7. Simplifies the control system components
The PLC also have counters, relays and other components, so it does not require components such as additional. Use of relays requires counters, timers or other components as additional equipment.
Printout of the PLC can be directly obtained and do not need to see the blueprint of his circuit. Unlike the printout relay circuit cannot be obtained.
Changing the PLC cannot be done unless the PLC is not locked and programmed. So there is no unauthorized person can change the PLC program for a PLC is locked.
10. Can make changes by reprogramming
Since the PLC can be programmed quickly reset the production process that mixes can be completed. For example part B will be executed but sections of A is still in the process, the process in section B can be re-programmed in seconds.
11. Addition of faster circuits
Users can add a circuit controller at any time quickly, without requiring great effort and cost as in conventional controllers.
Besides the benefits mentioned above, there are losses that are owned by the PLC, namely:
12. The technology is still new
Changing the old control system using relay ladder or to a PLC computer concept is difficult for some people
13. Bad for the application programs that remain
Some applications are applications with a single function. On application by one function rarely done did not even change at all, so the use of PLC in applications with a single function will be a waste (cost).
14. Environmental considerations
In a process, the environment may experience a high heat, vibration direct contact with electrical appliances within the PLC and this event continuously, thus disrupting the performance of the PLC is not functioning optimally.
15. Operating with a fixed circuit
If the circuit in an operation are not changed then the use of more expensive PLC compared with other control equipment. PLC will be more effective if the program on the process to be upgraded periodically.
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I am a programmer plc, and I worked in industrial automation.
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