Start and stop the motor with a single button. It can be programmed by the working principle of PLC’s sequential scanning. The working process of PLC is simply
First, the input sampling phase. PLC sequentially scans the state of the input terminals and stores the state of each input point in the input image register.
Second, execute the user program. For the ladder diagram, it is scanned first, then, and from turned left to right. The state of each touch of contact needs to be logically operated with the result of the previous logical operation, and the result is stored in the component image register or the output image register.
Third, the output is refreshed. The state of each point in the output image register is sent to the output latch, and the output latches drives the load of each output relay through the output terminal.
There are numerous methods, and the counter can of course be realized, but I don’t think it is necessary to kill the chicken with a knife! Here I only give three examples of the S7-200 PLC. See below: