Experimental Physics and Industrial Control System
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Hello colleagues,
we need some more detailed information (config-files) about the running configuration to give some hints for solving the described problem.
The HZB (former BESSY) didn't provide a OPC Server; we provide a EPICS
IOC-Shell with OPC driver support (OPC client) to get/put data from/to an existing custom-side OPC server. The OPC server is normally highly specialized to your PLC environment (here Beckhoff Ethercat) and is provided by the manufacturer of the PLC.
First I would start with a single EPICS-IOC-shell on the PC. Put the first some hundred channels into an OPC group and test it. This should be a well working configuration and should have a good performance.
If this configuration fails, you should take a closer look into the configuration of PLC / OPC-server. Otherwise add the next channels to the same IOC-shell but use a new OPC group. Repeat this step.
In the past we observed a much higher performance when using many smaller OPC groups instead of a large single one. Use different OPC groups for boolean and analogue values if possible. Adjust the OPC group update intervall as needed.
Unfortunately there is no experience of handling such a large number of channels on a single PC available.
Roland Fleischhauer / Carsten Winkler
Am 10.05.2013 16:18, schrieb Keith Thorne:
Dear colleagues
Here at LIGO we are setting up a Beckhoff EtherCat-based slow control system that we communicate with from our control-room through EPICS.
We are using the BESSY-developed EPICS OPC server to provide the interface.
The configuration is a Windows7 PC running both the EtherCat PLCs and the EPICS-OPC servers.
We use a recent EPICS-OPC release (based on 3.14.2)
We have followed BESSY guidelines regarding database settings and run multiple iocShells for EPICS-OPC that each have ~1000 channels (total is about 20,000 channels)
We are seeing the following problem.
1) Change EPICS variable for switch in control room
2) Change is transmitted to Beckhoff OPC quite rapidly and switch is changed on EtherCat OPC(< 1 sec).
3) Change in EPICS readback of OPC variable is slow, takes about 4 seconds (varies 2-6 seconds) even on EPICS client run on same Windows7 box
( This becomes even more fun when using a slider control in the control room…)
Has anyone else seen this behavior?
Should we move the EPICS-OPC server to a separate computer (but same LAN) as EtherCat OPC computer?
Should we run each EPICS-OPC iocShell in its own virtual Windows environment?
Thanks
Keith Thorne
------
Keith Thorne <[email protected]>
CDS Software Engineer
LIGO Livingston Laboratory
Livingston, LA 70754
Phone: (225)686-3168 Fax: (225)686-7189
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V.
Aufsichtsrat: Vorsitzender Prof. Dr. Dr. h.c. mult. Joachim Treusch, stv. Vorsitzende Dr. Beatrix Vierkorn-Rudolph
Geschäftsführung: Prof. Dr. Anke Rita Kaysser-Pyzalla, Thomas Frederking
Sitz Berlin, AG Charlottenburg, 89 HRB 5583
Postadresse:
Hahn-Meitner-Platz 1
D-14109 Berlin
http://www.helmholtz-berlin.de
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