We use a compound-cam twin arm structure and random tool access method to achieve a faster ATC (Automatic Tool Changer) system for the accurate position and rotation control of a tool magazine and an exchange am. Based on the data obtained from various sensors, it is possible to follow the sequence of commands in each control step for an exchange arm. However, it is not so easy to reduce the exchange time of the system because of the slow responses of the sensors and execution mode delays of PLC (Programmable Logic Controller) scan time. In this paper, we propose a new programmed limit-switch position control method to obtain the shortest possible delays for the random tool access method and compound-cam twin arm structure. With some experimental results, we have achieved below 0.9sec tool exchange time with the proposed method.