Status of the Control Sytem for the Front-End of the Spallation Neutron Source

Abstract

The Spallation Neutron Source (SNS) is a partnership between six laboratories. To ensure a truly integrated control system, many standards have been agreed upon, including the use of EPICS as the basic toolkit. However, unique within the partnership is the requirement for Lawrence Berkeley National Lab, responsible for constructing the Front End, to operate it locally before shipping it to the Oak Ridge National Lab (ORNL) site. Thus, its control system must be finished in 2001, well before the SNS completion date of 2006. Consequently many decisions regarding interface hardware, operator screen layout, equipment types, and so forth had to be made before the other five partners had completed their designs. In some cases the Front-End has defined a standard by default; in others an upgrade to a new standard is anticipated by ORNL later. Nearly all Front-End devices have been commissioned with the EPICS control system. Of the approximately 1500 signals required, about 60% are now under daily operational use. The control system is based on "standard architecture"; however, it has a field-bus dominated layout. This paper will discuss some unique interface requirements that led to adding new device families into the EPICS repertoire. It will also describe the choices and trade-offs made for all major areas.