J.G. Cramer and M.A. Howe
A paper describing the SControl system and program was presented in April at the AIHEN Conference held in Pisa, Italy.1 The program SControl, written in C++ and operating on a dedicated HP-712 workstation, was used intensively during the November-1995 run of CERN Experiment NA49. The principal tasks of SControl were: (a) to collect experiment-status information from 6 satellite processors, (b) to maintain an archive of this information by updating an archive file, (c) to provide user-controlled displays of experiment parameters of interest, and (d) to generate and manage alarms.
The experiment is represented in the SControl display by pages organized in a hierarchical structure, with a 'home' page at the top level showing an orthographic representation of the whole experiment. On this diagram the major subsystems were outlined in white, and each of these outlined regions provided a hyper-link to the top-level page of the subsystem. The subsystem top-level pages typically showed a block diagram of the subsystem, with blocks outlined in red providing hyper-links to the appropriate sub-sub-systems. This pattern of diagrams with hyper-links was repeated at one or more levels until a page was reached that was designed to monitor several related functions of a particular subsystem.
In the period between the 1994 and 1995 runs, the program was reorganized and restructured, and the code was analyzed with the diagnostic program PURIFY to discover memory leaks and other problems. This resulted in a much more stable code. In the 1995 run the program, except for a few startup problems associated with interfacing to the Macintosh and PC systems, operated very stably and with few crashes or operating problems.
A number of improvements were also made to the user interface. For example, the modification of display pages is now password protected. This eliminates the problem of operators changing display pages by accident. Real-time controls were added to the chart objects to allow operators to change charting parameters without having to know the password. In addition, the cut and paste functions were expanded to included whole page deletion and duplication, and alignment tools were added to make it easy to line up groups of objects along their edges or centers.
For the 1995 run of NA49 the hierarchical paging structure was extensively modified to include the two new time projection chambers and the increase in monitor inputs, particularly temperatures and gas condition readouts. In addition, the alarm system was modified to enhance the transmission and display of messages when an alarm is generated, and complete on-line documentation was produced providing a detailed description of the condition which generates each alarm and the actions the should be taken when the alarm occurs.