As digital substations move through the technology readiness scale to successful deployment, detailed modelling and testing is key for de-risking these schemes. Real-time simulation and hardware-in-the-loop testing are among the most comprehensive and cutting-edge tools available for testing protection and control schemes based on IEC 61850. The RTDS Simulator includes several options which support IEC 61850 and IEC 61869-9 Sampled Values, GOOSE Messaging, and MMS services. New to the RSCAD FX software is a combined Merging Unit model, which allows the RTDS Simulator’s GTNETx2 card to provide combined streaming services for SV, GOOSE, and MMS. Also new is native support for Parallel Redundancy Protocol (PRP) on the GTNETx2 card. This webinar will provide a brief introduction to digital substation testing with the RTDS Simulator, necessary testbed components, and the new models available in RSCAD FX. The presentation will be followed by a software demonstration.