OPC DA Connectivity

Full OPC DA server and client connectivity — plus a clear path to OPC UA

OPC DA (Data Access) is the most widely installed industrial connectivity standard in the world. KEPServerEX by Kepware includes a built-in OPC DA server, OPC DA client connectivity, and simultaneous OPC UA support — protecting your existing OPC DA infrastructure while enabling migration at your own pace.

What is OPC DA?

OPC DA (OPC Data Access) is the original OPC Classic standard, developed in the 1990s to provide a common interface between Windows-based HMI/SCADA software and industrial hardware. OPC DA uses Microsoft’s COM/DCOM technology for real-time data exchange between devices and applications on the same network. It remains the most deployed OPC protocol in brownfield industrial installations.

KEPServerEX as an OPC DA Server

KEPServerEX includes a high-performance OPC DA server that connects to over 150 native device drivers. Any PLC, RTU, controller, or meter connected through a KEPServerEX driver is immediately available to OPC DA client applications — including legacy SCADA systems, historians, and HMI panels that rely on OPC DA.

• OPC DA 2.05a and 3.0 compliance — full support for both versions of the OPC DA specification.
• Zero-configuration for OPC DA clients — DCOM-based OPC DA clients connect through standard OPC enumeration.
• LinkMaster for OPC bridging — link data between multiple OPC DA servers, acting as a universal bridge for OPC systems.
• RedundancyMaster — configure multiple OPC servers into redundant pairs to increase OPC data availability.

OPC DA to OPC UA Migration

KEPServerEX serves OPC DA and OPC UA simultaneously from the same installation. This means you can keep existing OPC DA clients running while new applications connect over OPC UA — no forklift upgrade required. As you modernise, simply point new clients to the OPC UA endpoint. Your device connectivity, tag configuration, and data quality stay exactly the same.

OPC HDA and OPC A&E

Beyond OPC DA, KEPServerEX also supports OPC HDA (Historical Data Access) for retrieving historical values from the server’s internal datalogger, and OPC A&E (Alarms and Events) for alarm and event subscriptions — giving OPC Classic clients full access to real-time, historical, and alarm data from a single platform.

How Allied Solutions Global supports OPC DA

Many plants across Southeast Asia run OPC DA as their primary connectivity layer. Our engineers understand the DCOM configuration, firewall rules, and security hardening required to keep OPC DA running reliably in production environments. We also plan and execute OPC DA-to-OPC UA migration projects when the time is right — with zero disruption to running operations.