Smart Manufacturing (SM) is the future of the manufacturing industry. Seamless, accurate, and fast connection and communications among devices are critical for SM. By leveraging information technologies, devices can dynamically communicate with each other to increase factory production, while decreasing engineering costs. MTConnect and Open Platform Communications - Unified Architecture (OPC-UA) standards facilitate such communication. MTConnect is a manufacturing interoperability standard that provides a semantic vocabulary for manufacturing equipment to provide structured contextualized data with no proprietary format. The OPC-UA is a platform-independent standard through which various systems and devices can communicate by sending messages between clients and servers over various networks. OPC-UA enables syntactic interoperability between clients and servers. The MTConnect - OPC-UA Companion Specification integrates the two standards to provide manufacturers more efficient and powerful interoperability capabilities. In this paper, we report the test of version 1.02 of this companion specification. This specification sets a standard means of communication between MTConnect devices and OPC-UA Clients/Servers based on Extensible Markup Language (XML) structures. To test the standard, the following components have been developed: an OPC-UA Server, an OPC-UA Client, a probe that translates data structures in MTConnect XML format to MTConnect OPC-UA Companion XML format that can be recognized by the server, a MTConnect XML data parser, and a MTConnect device simulator. The activities of the standard testing include passing varying data structures and objects through the server and confirming the information is received accurately by the client. The findings of the standard testing will be provided to the standard developing organizations for improving the future versions of the standard.