What are the similarities and differences between traditional relay-contactor control and PLC control?

"Relay-contactor" control: bulky, complicated wiring and difficult to modify.

PLC control: small storage logic volume, less wiring, flexible control and easy expansion.

2, the control speed is different

"Relay-contactor" control: the control function is realized by opening and closing the contacts, and the action speed is tens of milliseconds, which is prone to contact jitter.

PLC control: the control function is realized by semiconductor circuit, and the execution time of each instruction is in microsecond level, so there will be no contact jitter.

3, the time limit control is different

"Relay-contactor" control: it is realized by time relay, which has poor accuracy and is easily affected by environmental temperature.

PLC control: realized by semiconductor integrated circuit, with high precision, convenient time setting and not affected by environment and temperature.

4. Different reliability and maintainability "relay-contactor" control: short life, poor reliability and maintainability.

PLC control: long life, high reliability, self-diagnosis function and easy maintenance.