In this paper a new Software-in-the-Loop (SIL) strategy is proposed for real-time testing of Coordinated Volt/VAr Control (CVVC), through the use of the Real-Time Digital Simulator (RTDS) and Matlab® program. Such a strategy seeks to emulate, during the test, the interaction commonly established among the main layers of a Distribution Management System (DMS). To do so, a TCP/IP (Transmission Control Protocol/Internet Protocol)-based communication between the simulation module of the RTDS (RSCAD) and Matlab® is established. To prove the efficiency of the SIL strategy, an optimization technique based on Artificial Immune Systems is applied to deal with the problem of optimal CVVC in radial Distribution Networks (DNs) composed of multiple control equipment. Important aspects associated with the implementation of the test bed are discussed in this paper. Simulation results demonstrated that the proposed strategy is suited to analyzing the time domain behavior of CVVC designed for real-time operation in DNs.