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Architecture and standard hardware
We have adopted some hardware standards to focus
operational expertise, to limit device-dependent code
development, and to ease maintenance.
The standard DCS crate is a 6U VME chassis, it is equipped
with a Motorola MVME177 single board running VxWorks
as operating system.
Analog data are digitized by VME boards or directly on the
detector. In this latter case, CANbus is the standard bus
solution.
A Greensprings carrier board receive and transmit the CAN
messages.
A general monitor board has been developed to interface the
CANbus to the electronic placed on the detector.
Experimental Physics and Industrial Control System
• EPICS is used to control and monitoring the detector
subsystems, environmental conditions, and accelerator
parameters.
• EPICS is a freely distributed software package that includes
a real-time kernel running under the VxWorks operating
system, drivers for commonly used hardware components
(CAEN, CANbus…), and a suite of user applications for
control, monitoring, and data analysis.
• EPICS source code is written in C language and is available
for customization by the user.
• EPICS architecture is distributed, with the Input/Output
Controller (IOC) as the fundamental component.
DCS architecture
• The BaBar DCS is a distributed architecture based on a TCP/IP network of
15 IOCs containing about 105 hardware and software channels describing
the status of each subsystem and central system (gas and cooling system,
electronic house, interaction hall….)
• Each detector has one or more IOCs (VME + CPU) running is own EPCIS
software code and is able to communicate with all the others IOCs.
EPICS Channel Access
EPICS toll-kit contains a lot of tools connected via the
Channel Access client/server libraries.
EPICS Channel Access performance
EPICS software tools
• The EPICS internal database is used to define and store the records
(process block). 2500 records use around 1 Mbytes. For each records it
is possible to define a lot of fields and the most useful are: the scan rate
(max 60Hz), the operating range, the alarm limits, the alarm severity, the
archive deadband….
• The State Notation Language is used to build state machines. The I/O
variables of the state machines have to be defined EPICS records. The
state machines run in the VxWorks environment.
• For the visualization has been used the EDD/DM tool that provides an
interactive display editor and high performance display manager; but
different tools are available from JAVA to tcl/tk and from LabVIEW to
Visual Basic. DM is able to update about 2000 channels per second.
• ALH is the alarm handler providing alarm viewing, logging and
annunciation. It can handle up to 500 alarm condition changes per
second.