OPC Device Support Bernhard Kuner Carsten Winkler BESSY

OPC - Device Support Bernhard Kuner, Carsten Winkler BESSY, Berlin, Germany Berliner Elektronenspeicherringgesellschaft für Synchrotronstrahlung mb. H (BESSY)

Introduction to OPC • OPC: OLE (COM) for process control DCOM: Distributed Component Object Model • Client/Server scalable and distributed over network • “Data Access” specification read/write, time stamps, quality polled or callback • “Alarm and Event” specification Existing OPC servers support only a subset of the defined OPC features Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

Data Flow • Device - OPC server communication: proprietary, vendor dependant • OPC client - OPC server communication: via DCOM (Microsoft) • OPC libraries available for: all Windows, Unix, not vx. Works Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

Client Data Access • Connect to server Client will start/stop the server • Add group Client defines groups with common parameters for all items within the group • Add items Client subscribes for several data objects Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

Bessy Installation • Connect PLC controlled beamlines to EPICS - 30 PLCs: c. 6, 000 PVs - 4 OPC servers - Currently 600 PVs with the new ioc. Shell - In the future: 30, 000 PVs • Data volume One PLC: 6 k. B/s, polled with 50 ms - > 2 GB/d raw data over the network - > 200 k. B Channel Access data Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

Former Approaches • OPC_CAS – Doesn’t work reliably – Several crashes a day • Visual. Basic program with Kepware OPC client and Active. X_CAS - Proper handling of values, alarms and graphic limits - Crashes ALH and other clients - No access security - OPC can’t set STAT and SEVR • XCas – Another CAS based solution Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

Device Support for EPICS 3. 14 • For these record types: - ai, ao - bi, bo - mbbi, mbbo - mbbi. Direct, mbbo. Direct - longin, longout - stringin, stringout - (waveform) • OPC client with - Softing OPC Toolbox 3. 01 - Other client libraries possible Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

opc. Dev. Sup Features • Data conversion for all integer and float data types • Timestamp generated by OPC server or EPICS determined by the record‘s TSE field • Map OPC quality to records STAT/SEVR fields • Out records may be written by the PLC and by EPICS in - records: read only records out - records: read/write records • Record processing: SCAN field: „I/O Intr“ or „. 1 second“ to „ 10 second“ OUT records are not „Passive“, but „I/O Intr“ Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003

Conclusions • Portable CAS solutions never satisfy EPICS clients. • For full range of EPICS functionality EPICS records are required. Kuner, Winkler: OPC Device Support – EPICS Collaboration Meeting at Diamond, June 2003