OPC Server types

 📘 Types of OPC Servers / KEPServerEX – Detailed Notes

🔹 1. Overview

OPC Servers come in different types, defined by the OPC specification they implement. Each type serves a different purpose — such as real-time data, alarms, historical logs, or unified secure communication.

KEPServerEX supports several of these types, making it a comprehensive, multi-protocol data server.

🔸 2. Types of OPC Servers

OPC Server Type Full Form Purpose Supported in KEPServerEX?

OPC DA Data Access Real-time data (read/write) from devices like PLCs ✅ Fully Supported

OPC UA Unified Architecture Cross-platform, secure communication; supports complex data ✅ Fully Supported

OPC A&E Alarms & Events For event-driven systems: alarms, warnings, conditions ✅ Supported via plugin

OPC HDA Historical Data Access For accessing logged/historical time-stamped data ✅ Supported via plugin

OPC XML-DA XML Data Access Web service-based access to OPC data ❌ Deprecated in favor of UA

🔹 3. Details of Each OPC Server Type

🟩 A. OPC DA (Data Access)

Purpose: Real-time data exchange between OPC server and client.

Used For: PLC tag reads/writes, real-time monitoring

Communication: COM/DCOM (Windows only)

Data Type: Simple data (Int, Float, Boolean, String)

🔧 KEPServerEX:

✔ Native support for OPC DA 1.0, 2.05a, and 3.0

✔ Most widely used in legacy systems

✔ High-speed real-time data transfer

🟦 B. OPC UA (Unified Architecture)

Purpose: Modern, platform-independent, secure communication

Used For: IIoT, cloud integration, secure multi-platform data exchange

Communication: TCP/IP, HTTP, HTTPS (cross-platform)

Data Type: Supports complex data structures, objects

🔧 KEPServerEX:

✔ Full support with built-in OPC UA server

✔ Encryption, certificates, role-based access

✔ Preferred for new systems and IIoT/cloud solutions

🟨 C. OPC A&E (Alarms & Events)

Purpose: To detect and report system alarms, events, conditions

Used For: SCADA alarms, HMI alerts, exception handling

Event Types: Simple, Tracking, Condition

🔧 KEPServerEX:

✔ Supported via Alarm & Event Plug-in

✔ Sends real-time alarm/event data to OPC A&E-compliant clients

✔ Useful in monitoring abnormal plant conditions

🟧 D. OPC HDA (Historical Data Access)

Purpose: Accessing time-series/logged data

Used For: Reporting, trend analysis, data logging

Time-based Queries: Range, interpolation, aggregate data

🔧 KEPServerEX:

✔ Requires DataLogger Plugin or integration with databases

✔ Can log OPC DA data to SQL, CSV, or historian

✔ OPC HDA clients can read this logged data

🟥 E. OPC XML-DA (XML Data Access) (Rare/Deprecated)

Purpose: Use of XML/SOAP for OPC communication via web services

Limitations: Slow, complex, replaced by OPC UA

Status: Deprecated in modern systems

🔧 KEPServerEX:

❌ Not supported (as OPC UA is the preferred alternative)

🔹 4. Additional KEPServerEX Capabilities Beyond OPC

Feature Description

MQTT Server / Client Publish OPC tag data to cloud or broker (e.g., AWS, Azure)

RESTful API Access tags via web clients, dashboards

SNMP Support For monitoring IT devices (e.g., routers, switches)

Modbus, Siemens, Rockwell drivers Native industrial protocols integration

These make KEPServerEX a Universal Industrial Gateway, not just an OPC server.

🔹 5. Visual Summary – KEPServerEX OPC Support

pgsql

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┌───────────────────────────────────┐

│ KEPServerEX │

├───────────────────────────────────┤

│ ✔ OPC DA | Real-time data │

│ ✔ OPC UA | Secure IIoT & Cloud │

│ ✔ OPC A&E | Alarms & Events │

│ ✔ OPC HDA | Historical Logs │

│ ❌ OPC XML| Deprecated │

├───────────────────────────────────┤

│ + MQTT, REST, SNMP, DB Logging │

└───────────────────────────────────┘

✅ Final Summary

Aspect Explanation

OPC DA Legacy, fast real-time data (COM/DCOM)

OPC UA Modern, secure, scalable (TCP/IP)

OPC A&E For alarms, event notifications

OPC HDA Accessing time-series/historical logs

KEPServerEX Supports all major OPC server types + industrial protocols + cloud connectors