OPC evolution toward Unix Mark Beharrell IT/CO, CERN, Geneva, Switzerland ICALEPCS ― October 12th, 2005 ►Communication standards within a DCS ►OPC Data Access ►OPC on Unix ►The future From Windows to World Wide Domination?

2 Data Flows within a Detector Control System Devices Supervisor (SCADA) Accelerato r Experiment Safety General Services Web Access DCS

3 Device communication Device access protocols vary between:- Manufacturers Models Versions of models Want an ‘interpreter’ Hide device differences Developed by 3 rd party What protocol to use with the interpreter?

4 Middleware General solutions CORBA Java RMI DCOM General solutions are not sufficient Must solve a specific problem in standard way Need Standardize to level of the device “Data Acquisition” “OPC Data Access”

5 The OPC DA solution OPC Data Access 1.0 Well defined specification giving Device model Data model Communications model Acceptance Wide user base Uses DCOM middleware

6 Why OPC on Unix Motivation Single protocol for all device oriented communications Possibilities 1.DCOM on Linux 2.OPC XML DA 3.OPC Unified Architecture

7 1. DCOM on Linux 1996 – Microsoft release the DCOM Spec. Implementations on Solaris, VxWorks, Linux DCOM → OPC OPC DA (DCOM) Servers on Linux Performance? Stability?

8 1. DCOM-Performance & stability Test Windows OPC server ported to Linux Measured time to read OPC items (float) on both platforms Result Windows OPC ~ 100,000 items per second Linux OPC ~ 76,000 items per second Problems OPC server itself was stable ‘System issues’

9 2. OPC XML DA 2003 – OPC XML DA released Similar to the DA specification Same device and data model Different communication model Based on Web Services OPC XML DA on any TCP/IP enabled processor

10 2. XML-Performance & stability Test Wrote OPC XML server using toolkit. Measured time to read OPC items (float) on both platforms Result OPC XML DA ~ 6,000 items per second Verses 76,000 with OPC on Linux! Problems ~5 items per second for single OPC item reads! Interface definition does not always translate to code correctly.

11 3. OPC Unified Architecture 2005 – OPC UA introduced But not yet released Fusion of OPC interfaces “Integration of plant floor data into enterprise systems and the internet” Provide secure, reliable and efficient services Protocol and platform independence DCOM to be ‘retired’ Replaced by SOAP based alternatives

12 It works but is it useful? Several solutions to OPC servers on Unix. DCOM based OPC XML DA OPC UA Waste of time ? - NO OPC DA clients on Linux based SCADA systems. Low industrial acceptance Not yet available

13 Into the future OPC DA lives for the time being OPC XML will be replaced by UA OPC UA holds promise. Platforms But World Wide Domination? Enterprise Factory Internet For device access – maybe!