The Basic difference between PLC and Microcontroller

The basic difference between PLC and Microcontroller is as below.

1. The IO capacity of PLC is more than Microcontroller, Microcontroller does not have IO capacity in thousands.    example :    Temperature value 56 celcius,  you need I/O for Upper limit, lower limit, standart limit, alarm etc. each value needs I/O.

2. PLC having more than one CPU or Processor inbuilt where Microcontroller  does not have.

3. Watchdog for the PLC is faster than Microcontroller , means scan cycle time of PLC is more than Microcontroller.

4. PLC has a redundancy in failure condition, Microcontroller does not have.

5. PLC (Remote IO) can be placed and operated in hazardous area, Microcontroller can not work in that type of area.

6. PLC can communicate on different protocols , Microcontroller can not support all protocols.

7. PLC is more reliable and robust to use for industrial application so controller failure possibility is very less in case of PLC, where Microcontroller can fail any time.

8. Microcontrollers are not designed with the ruggedness and ability to withstand extreme conditions like PLCs. This makes them not ready for industrial applications.

9. Industrial sensors and actuators are usually designed according to the IEC standard which is usually at a range of current/voltage (24V DC) and interfaces which may not be directly compatible with microcontrollers and will require some sort of supporting hardware which increases cost.

WHICH ONE THE BEST FOR DATA AQUISITION?

It really depends on realtime and functional safety requirements. If you need hard realtime response, MCU based PLC is still the right choice.  If  realtime is no needed, simple remote actuators and sensors where the logic and algorithm are centered at industrial datacenter much better in low price.