Correct Answer - Option 4 : programmable
The term PLC stands for the Programmable Logic Controller.
PLC is known as a ‘hard real-time system’.
The mass advantage of PLL over ‘hard-wire’ type relay control systems, is that PLC land themselves is functional changes very easily.
Mass components of PLC are:
- Rock or chassis
- Power supply
- Central Processing Unit (CPU)
- Communication modules
- Input and outputs
Modes of operation of PLC: There are two modes of operation:
It is used to enter a new program, edit or update the existing program, upload files, and download files. Also, in this mode of operation, all outputs are de-energized.
It is used to execute the user program. Remote PLC programming or mode selection is dissolved when the keys are in the Run mode position. In this mode, the output is energized. It does not allow program entry editing in this mode of operation of PLC.