A factory line system includes a series of robot arms arranged alongside a conveyor on which workpieces are transported. Each workpiece is fitted with a data carrier and each robot arm is fitted with a reader/writer that can wirelessly communicate with the data carrier of each workpiece when the latter is in transit between the conveyor and a work station. Specifically, when a first robot arm detects a workpiece, it removes the workpiece from the conveyor to a first work station that performs work on the workpiece and sends result data through the reader/writer of the robot arm to the data carrier and replaces the workpiece from the first work station to the conveyor. When the workpiece is transported, approaching a second robot arm, the latter reads the result data through its reader/writer from the data carrier. According to the result data, the second work station performs work on the workpiece.