1) Flexibility. 2) Implementing changes & correcting errors. 3) Speed of operation. 4) Reliability & maintainability. 5) PLCS are smaller in size & can operate Number of devices at a time. 6) Logic change can be very easily done by just adjusting the ladder logic. 7) Operation of PLC can be displayed on CRT or LCD screen. 8) Error occurred in operation can be very easily observed and diagnosed.