The project is to arrange four color led lights, controlling them to blink in a certain order. 

This is my first time programming on a PLC. The programming method is quite strange, using latter method, but I still prefer coding style, which is fast and efficient.

The final score is dependent on programming speed, but unfortunately, we met some bugs, and took an hour before we solved, so failing to get an A...a little upset.

The PLC is more powerful than common single chip board, but I suppose it is rare for me to expose to it again..

Programming "ladder"

might be helpful to future students..