Industrial plants suffer from a high degree of complexity and incompatibility in their communication infrastructure, caused by a wild mix of proprietary technologies. This prevents transformation toward Industry 4.0 and the Industrial Internet of Things. Open platform communications unified architecture (OPC UA) is a standardized protocol that addresses these problems with uniform and semantic communication across all levels of the hierarchy. However, its adoption in embedded field devices, such as sensors and actuators, is still lacking due to prohibitive memory and power requirements of software implementations. We have developed a dedicated hardware engine that offloads processing of the OPC UA protocol and enables the realization of compact and low-power field devices with OPC UA support. As part of a proof-of-concept embedded system, we have implemented this engine in a 22-nm FDSOI technology, representing the first ASIC implementation of an OPC UA server. We measured performance, power consumption, and memory footprint of our test chip and compared it with a software implementation based on open62541 and a Raspberry Pi 2B. Our OPC UA hardware engine is 50 times more energy efficient and only requires 36 KiB of memory. The complete system consumes only 24 mW under full load, making it suitable for low-power embedded applications.