QJ71C24N—R4Overview of Mitsubishi QJ71C24N R4 The Mitsubishi QJ71C24N R4 is a dual port serial communication module for MELSEC Q series PLCs. It supports RS 422 and RS 485 communication standards with two independent ports, allowing connection of multiple external devices or networks. This module facilitates high speed and reliable serial data exchange for industrial control applications. Key Features of Mitsubishi QJ71C24N R4 Dual Serial Ports: Two RS 422 485