When your plant has multiple OPC servers from different vendors, how do you get them exchanging data reliably without running physical wiring between every system? OPC Expert Bridge solves this by acting as a multithreaded client that reads from one OPC server and writes to another, regardless of vendor, protocol version, or network location.

Chapters

0:04 — Welcome and what we’ll cover
1:40 — Why OPC servers can’t talk
5:38 — What a reliable bridge requires
10:06 — Inside OPC Expert’s architecture
17:01 — Installing and opening OPC Expert
20:37 — Setting up bridges manually
26:04 — Exporting and bulk-editing bridges
29:45 — Running the bridge as a service

Webcast Summery

OPC servers, by design, only respond to requests; they cannot initiate communication with each other. A dedicated bridge client is required to sit between them and move data in either direction. OPC Expert handles this across OPC DA and OPC UA, locally or over a network, with support for mixed protocol conversions and redundancy configurations.

Key capabilities and takeaways from the OPC Expert Bridge interface:

  • Dual-pane browser view displays both the source and destination OPC server trees side by side, letting you set up a bridge by dragging a tag from the source tree and dropping it onto the destination tag.
  • Live status indicators show each bridge connection in real time using green checkmarks for healthy links and red X marks for failed ones, so you can assess system health at a glance without parsing log files.
  • Summary view provides an at-a-glance count of configured bridges and their overall connection state, which is especially useful when managing hundreds or thousands of tags where reviewing each item individually is impractical.
  • Items view exposes per-bridge detail including source item ID, destination item ID, data type, timestamp, quality, and live values, with automatic data type conversion handled transparently between mismatched types such as INT32 and FLOAT.
  • CSV export and import lets you export your current bridge configuration to a spreadsheet, bulk-edit or build out thousands of additional bridge entries in Excel, then import the file back, dramatically reducing setup time for large deployments.
  • Windows Service installation is available directly from the Tools menu, allowing OPC Expert Bridge to start automatically with Windows under the local system account or a named user account, with no active user session required.

The bridge GUI is not just a setup tool; it is your diagnostic window into a running service, giving you visual confirmation of what is working and what is not without ever opening a log file.

OPC is extremely common in industrial automation. Plants typically already have OPC servers in place for a variety of systems, which makes OPC an attractive communication platform. The challenge isn’t finding OPC servers — it’s getting them to share data with each other.

The Problem: OPC Servers Cannot Communicate Directly

Two OPC servers, regardless of vendor, cannot communicate with each other directly. The reason is architectural: OPC servers only respond to requests — they do not initiate them. With two servers and no client, there is nobody to make the request. You need a third-party client application to read data from one OPC server and write it to the other.

This applies no matter which vendors supply the OPC servers, and those servers do not need to come from the same vendor. The bridge sits between them and handles the data transfer in both directions.

Requirements for a Reliable Bridge

The alternative to OPC-based communication is running physical wires between systems — costly and inflexible. That means an OPC bridge needs to meet a high bar for reliability. Key requirements include reliable data transfer with support for OPC redundancy and bridge redundancy; a multi-threaded design so that if one OPC server stops responding, the other communication paths are not affected; visual status reporting so operators can see what is happening without digging through log files; support for thousands of bridges simultaneously; reduced setup and integration time; and the ability to run as a Windows service, starting automatically with the operating system even when no user is logged on.

The multi-threading requirement deserves emphasis. Many bridges are not multi-threaded, which means a single unresponsive OPC server can freeze all communication across every connection. That is not acceptable in a production environment.

OPC Expert: Key Features

OPC Expert addresses these requirements with a multi-threaded architecture and broad OPC support: OPC UA, OPC Classic (DA), OPC tunneling, and OPC redundancy are all supported. Local and remote OPC servers are supported interchangeably. You can connect OPC DA to UA, UA to DA, or DA to DA — mixing protocols and mixing vendors. Security profiles for OPC UA, OPC Classic on domains and workgroups, and transport via DCOM, TCP/IP, HTTP, and HTTPS are all included. The software runs on Windows XP through Windows 11 and Windows Server 2003 through Windows Server 2025.

Beyond bridging, OPC Expert includes an OPC DA server, an OPC UA server, Excel connectivity, a full MQTT pub/sub system with a built-in broker, SQL and CSV data storage, and a REST API for accessing OPC data on non-Windows platforms such as Linux, mobile devices, and tablets. This webinar focuses specifically on the bridging modules — DA client to UA server, and UA client to DA server — but the full feature set is worth knowing.

Setting Up Bridges Using the GUI

OPC Expert is a portable executable with no installer and no changes to the Windows registry. To start it, double-click the executable. To remove it, delete the files. Nothing is left behind.

To begin bridging, enable the bridge GUI under the View menu. OPC Expert automatically discovers OPC DA and UA servers on the network. You can optionally display the right-hand tree, which shows the same server and tag structure as the left-hand tree and is useful when dragging sources to destinations.

To create a bridge, connect to your source OPC server, browse to the tag you want, and drag it to the corresponding tag in the destination OPC server. OPC Expert creates the bridge, assigns a name, and displays a summary. Clicking Start initiates the data transfer. In the items view you can watch each bridge in real time: source and destination item IDs, user-friendly names, timestamps, quality indicators, and data types are all visible. OPC Expert handles data type conversion automatically — integers to floats, strings to integers, and so on.

Because the engine is multi-threaded, you can add bridges in any order without waiting for existing ones to connect. Bridges created through the GUI are well suited for small configurations or for building an example that you then export and expand.

Exporting, Editing, and Importing Bridge Configurations

For large deployments, the GUI approach does not scale. OPC Expert addresses this by allowing you to export your configuration to a CSV file. Go to File, then Import/Export, then Export CSV. You can select which fields to include — the minimum set covers source and destination item IDs — and save the file to disk.

The exported file is a standard CSV that opens in Excel or any text editor. You can copy and paste rows to duplicate bridge definitions, modify source and destination paths, and add as many rows as needed. Thousands of bridges can be defined this way in a short time.

To import the configuration, either go to File, Open and select the CSV, or drag the file directly onto the OPC Expert window. OPC Expert reads the bridges, displays them, and waits for you to click Start. The same export-edit-import cycle works whether you are building from scratch or updating an existing deployment.

Running as a Windows Service

Once the bridge configuration is confirmed and working, you can install OPC Expert as a Windows service so it starts automatically with the operating system and runs without anyone logged on. Go to Tools and select Install as Windows Service. You can run it under the local system account or a specific user account, depending on whether you are connecting to local or remote OPC servers and whether your network is a workgroup or a domain.

After installation, OPC Expert Bridge Server appears as a running service in Task Manager. Closing the OPC Expert GUI does not stop the service — data transfer continues in the background. To check status visually at any time, simply open the GUI again. It connects to the running service immediately and displays the current bridge status without interrupting anything.

Obtaining the Software

OPC Expert and OPC Rescue are available for download at opcexpert.com and opcrescue.com. OPC Expert supports trending, bridging, tunneling, archiving, and more. This webinar covered bridging specifically, and additional webinars are available for the other capability areas.

OPC Training and Certification

Hands-on OPC training is available through vendor-neutral workshops where participants earn a Certified OPC Professional designation. Courses cover configuring DCOM and OPC UA, troubleshooting OPC systems, securing OPC communications, and OPC best practices. Each participant works with a client computer and a server computer, configuring and troubleshooting systems directly. Workshops are delivered remotely with a live instructor in public cohorts or as private sessions for individual companies, either remote or on-site. Course dates are listed at opcti.com.