This session focuses on smart sensors and their interoperability issues. It first explains what constitutes smart sensors. It then describes IoT and CPS requirements for smart sensors and the interoperability of smart sensors from different manufacturers is essential for data and information exchanges. This session discusses how interoperability is defined, how to conduct interoperability tests, and what typical testing method can be applied for smart sensors. For further clarification, it shows some standards-based smart sensor interoperability test cases, e.g., IEEE 1451.0 and 1451.5, IEEE 1451.5-802.11, IEC 61850-9-2, and IEEE C37.118. These cases have been studied at the National Institute of Standards and Technology (NIST) Smart Grid and CPS testbed. The interoperability testing method can help sensor manufacturers, sensor system developers and integrators to develop and test standard-based interoperable smart sensor products to achieve sensor data interoperability and plug & play in IoT and CPS applications.