Abstract: The test system provides conventional analog outputs that allowing application of power system conditions simulation to a device under test. The test device has a communication interface which sends and receives digital communication to and from protection relays, control devices, and meters, known as intelligent electronic devices (IEDs). The test device interacts with the devices under test over a direct communication link or a substation local area network. The communication protocol includes digital communication to send and receive messages which simulate virtual switching and control equipment status and other intelligent electronic device (IED) data and status. The test system monitors the operation of the IED device under test based on the IED digital communication data received and the contained control signal status utilizing the digital communication interface as a substitute for the conventional hard-wiring of IED binary inputs and outputs.