Digitizer IOCs

Digitizer IOCs

The IOC, or Input/Output Controller of a VME crate is an MVME5500E embedded processor module. The processors use the [[vxWorks operating system. VxWorks is capable of supporting multiple concurrent threads. The major thread types used in the Digital Gammasphere setup are shown in the white boxes within the picture of the IOC.

EPICS

EPICS, or the Experimental Physics and Industrial Control System, is the main thread that runs on the IOCs. EPICS implements a distributed database architecture in which a large number of Process Variables (PVs) are distributed across multiple processors. In Digital Gammasphere the mesh of processors consists of

• Eleven MVME5500s that each manage one VME backplane with four digitizer modules (VME01, VME02, ..., VME11)
• One MVME5500 that manages the VME backplane where the trigger modules are plugged in (VME32)
• The Linux computer DGS1, that is hosting two different processing threads related to EPICS:
  • The "Soft IOC" program that acts like all the other IOCs, participating in the shared database; and
  • The "DGSCommander" GUI that links GUI controls (buttons, indicators, drop-downs, graphs, etc.) to PVs in the distributed database.