TU Darmstadt, Darmstadt, Germany
Archiving systems based on relational databases (RDB) provide a higher flexibility with regard to data retrieval and analysis than the traditional EPICS Channel Archiver. On the other hand they can suffer from poor performance compared to the Channel Archiver for simple linear data retrieval operations. However, careful tuning of the database management system's configuration can lead to major performance improvements. Special care must be taken to ensure data integrity following power outages or hardware failures. This contribution describes the hardware and software configuration of an archiving system used in the production environment at the S-DALINAC. It covers performance and reliability aspects of the hardware as well as tuning of the Linux operating system and PostgreSQL server optimizations.
TU Darmstadt, Darmstadt, Germany
A large number of devices used at the S-DALINAC are controlled by IOCs running on standard personal computers via CAN bus (Controller Area Network). CAN interface controllers for PCs are commercially available from different manufacturers but although they all share the same basic functionality, most of them have a vendor-specific API. Moreover, traditional CAN drivers can usually be accessed by only one process at a time which avoids the use of sniffer programs for debugging. In contrast to that the SocketCAN network stack [1], included in recent Linux kernels, provides access to the CAN bus via network devices (BSD sockets) which can be accessed by multiple applications at the same time via a vendor independent interface. A set of open source CAN drivers provides access to controllers of different vendors. This contribution describes an EPICS device support that makes use of the SocketCAN framework and thereby is independent from the API of a specific vendor. The device support has been used successfully in a production environment at the S-DALINAC since almost two years.
[1] http://developer.berlios.de/projects/socketcan/
TU Darmstadt, Darmstadt, Germany
The S-DALINAC is a recirculating superconducting electron LINAC which has been in operation for twenty years. The control system had been developed in-house and, while being moderately reliable, has become very hard to maintain and nearly impossible to adapt to new requirements. The replacement of the old analog low-level RF control system by a modern digital solution in 2010 became a primer for the introduction of an EPICS-based control system. Several important subsystems have been migrated since then, but the process has not been completed yet. This contribution overviews the current status of the new control system and developments planned for the future. Basic hardware aspects are described as well as client software and operator interfaces. The general network infrastructure has been restructured in context of the ongoing migration and is also presented.