Manufacturing automation systems are widespread and becoming more common across the world. Therefore, fieldbuses of automation systems in a factory plant becomes distant and dissimilar technologies from one another. Realtime interconnection between these fieldbuses is essential for the sustainability of automation. This study designs a system that provides a realtime, remote communication among WorldFIP, CAN, PROFIBUS fieldbuses over ATM backbone. Fieldbuses are connected to backbone with bridges. Using network simulation software under various message traffic, the designed system's performance is investigated and the obtained results from the simulations are discussed. The results showed that fieldbuses can communicate with each other based on realtime requirements over ATM.