Recently, Real-time Ethernet has become popular communication technology in automation system applications due to its high bandwidth capacity and low market cost. In addition, CC-Link IE Field has been successful in combining the ultra-high speed feature with the large amount of data to be transferred while integrating in field-level industrial communication networks. This protocol also provides a seamless structure that provides the ability to implement a gateway to communicate with different protocols. On the other hand, many devices such as motor driver still apply CAN or serial RS-485 in automation systems, which means that CC-Link IE Field requires time and cost to allow these devices to implement this new protocol. In order to alleviate this problem, this paper proposes a method of designing a gateway for communicating between the CC-Link IE Field and serial RS-485 based protocol to increase the adoption rate of using CC-Link IE Field in automation system networks. This gateway structure was implemented and verified in experiments of using CC-Link IE Field Master to control motor drives, thus supporting the RS-485 communication interface.