The latest cultivation research and development of seeding technology was improved because the demand for direct planting increased. The Programmable Logic Controller (PLC) and position sensor are utilized to control the seed detection system. In this paper, of seed types, RPM (Revolution per minute) variations and hole size are considered to determine the capacity of seeder hopper to meet the needs of customer demand. These algorithms were composed of the process of seed monitoring and the compulsion opening system. The capacity of seeding is assumed to be 1.53kg(11.6 liters) of rice seed per 1.8km. Therefore, this detection system can be used to determine the capacity according to seed types, RPM and hole size.