Lessons Learned Enhancing EPICS CA for LANSCE Timed and Flavored Data
J.O.Hill* (LANL)
A previous paper described an upgrade to EPICS enabling client side tools at LANSCE to receive subscription updates filtered selectively to match a logical configuration of LANSCE beam gates, as configured by a user in the control room. To accommodate the upgrade fundamental changes were made in the EPICS core components. First, the event queue in the EPICS server was upgraded to buffer record (function block) and device specific parameters accessed generically via new software interfaces for introspection of 3rd party data. In contrast, the event queue in previous versions of EPICS was strictly limited to buffering only value, timestamp, and alarm status tuples. Second, the Channel Access server was upgraded to filter subscription updates. To make the filtering agent very flexible at runtime, filtering is accomplished by runtime interpretation of byte code generated from filtering expressions provided by the subscribing client. In this follow on paper, the performance of the new system, our future plans, and the lessons learned during this software development project will be described.
Work supported by US Department of Energy under contract DE-AC52-06NA25396.