Siemens S7 PROFIBUS/MPI OPC UA Server Release Notes

A summary of updates to the Siemens S7 PROFIBUS/MPI OPC UA Server, including new features, improvements, and bug fixes. Use this page to track changes that may affect system operation and integration.

v3.14.0

16 Apr 2026

Install →

Bug fixes:

Fixed an issue in the caching mechanism that could, in rare cases, incorrectly trigger a cache miss. As a result, clients could receive a "no data" error even though valid data was already available in the server cache.

v3.13.0

14 Apr 2026

Install →

This release serves as a baseline milestone representing the current state of the Siemens S7 PROFIBUS/MPI OPC UA Server. Starting with version 3.13.0, all subsequent releases are published on dpaxt.com.
Previous releases introduced significant improvements to the S7 over ONLINX communication layer, including transaction processing, connection management, and resilience against low-level communication errors. The request/response processing model was redesigned, robust connection recovery mechanisms were added to handle incomplete or corrupted responses, and overall stability was significantly improved for unreliable MPI and PROFIBUS connections.
The server's functionality was also expanded with support for the primary S7 memory areas, improved batch read processing, and enhanced handling of data status errors. Reliability was further increased through proper connection cleanup and improved handling of stalled transactions. Particular attention was given to compatibility with legacy automation systems and stable operation on Windows NT4 and Windows 2000 environments.
At the platform level, numerous enhancements were made to improve stability and portability. These include updated build infrastructure, improvements to network adapter and HID handling, and increased overall reliability of the OPC UA server during long-term operation.