Integrating EPICS and MDSplus

The National Spherical Torus Experiment (NSTX) has been in operation at the Princeton Plasma Physics Laboratory (PPPL) since 1999. Since then, NSTX has made use of the Experimental Physics and Industrial Control System (EPICS) and MDSplus software packages, among others for control and data acquisition. To date, the two products have been integrated using special ‘bridging’ programs that include client-components for the EPICS and MDSplus servers. Recent improvements in the EPICS software have made it easier to develop a direct interface with MDSplus. This paper will describe the new EPICS extensions developed at PPPL that provide: (1) a direct data interface between EPICS process variables and MDSplus nodes; and (2) an interface between EPICS events and MDSplus events. These extensions have been developed for use with EPICS on Solaris and are currently being modified for use on real-time operating systems. Separately, an XML-RPC client was written to access EPICS ‘trended’ data, sampled usually once per minute during a 24 h period. The client extracts and writes a day's worth of trended data to a ‘daily’ MDSplus tree.