There are many advantages of PLC
a.The PLC was specifically designed for harsh conditions with electrical noise magnetic fields vibration extreme temperatures or humidity.
b.By design PLC are friendlier to technicians since they are in ladder logic and have easy connections. Languages are typically fixed to ladder logic functions block or structured next.
c.PLC in rack from are easy to exchange and add parts. They are designed for modularity and expansion.
d.PLC execute a single program in sequential order. These have better ability to handle event sin real time.
e.A PLC never crashes over long periods of time.
f. A PLC has is the ability to simulate I/ O. Assuming the program structure buffers raw I/O to a local buffer structure it is fairly easy to simulated devices such as motors or valves that have feedback.