For the control cabinet of automatic spraying line, we have many successful cases in the application of automatic spraying industry, including one spraying and one baking, two spraying and two baking, three spraying and three baking, etc. for the programming of automatic spraying line, we use PLC to communicate with multiple frequency converters through 485 (up to 38), so as to realize the automatic centralized control of the whole line, which is clean and easy to maintain.