A method and system for interoperability testing is provided. Various network communications messages are sent to a device under test (DUT) and a number of similar devices from different sources including different manufacturers. Responses to the test signals from the device under test and the similar devices are compared to expected responses in accordance with the standard, and adjustments are made in the device under test if deviations in responses are detected. The device under test may be a intelligent electronic device or IEC 61850 protocol client device.