Naming Convention
Background
EPICS will supply the base elements, as `channels', for most of the
named elements in the Subsystems Slow Controls part of Online that come
from VxWorks on VME processors. Component objects (`Proxies') will be
built from these, implemented as Unix processes for Online Detector
Control. Diagnostic tools will access EPICS elements directly using
Channel Access; standard ODC tools will access the Proxies using a
different name space.
EPICS will also provide the mechanism foraccessing monitor values from
the Dataflow ROC and ROM processors to the (dynamic) Dataflow proxies.
The restrictions of Channel Access itself will constrain the naming of
the base elements. The bulk of the electronically derived quantities
and software-process (much of upstream Dataflow) derived quantities
will first be accessed from EPICS as base elements. The names will
therefore show up on schematics, wire-lists, and as VxWorks symbols.
These in turn will be reported out from one or more project databases
containing a great variety of other related information.
The Component names will be used to store the collected data into the
Conditions database and to retrieve setpoints from the Configuration
database. Thus these names will appear extensively in analysis, setup,
and calibration software.
Constraints
Channel Access and EPICS possess a flat namespace and a discovery
protocol that require all integrated components have channel names that:
- are unique
- are less than 28 characters in length
- have no embedded non-alphameric characters other than `
:
'
and `_
'
(and possibly a few more)
Desirable Items
- The name should make explicit the hierarchical, shared view that is most natural.
- A balance should be struck between intelligibility and brevity;
insofar as simple string-match tricks will have to be used for
name selection, the convention should help, not hinder this.
- The mapping from channel names to component name should be obvious.
Proposal
Each name will have the form:
<sub>:<area>:<type>:<dev>_<quant>_<serial>
where:
<sub>
- is the subsystem, one of {DRC, EMC, DCH, SVT, IFR} see below for current list
These are intended to be detector subsystems and other
independent, logical, geographic or administrative entities.
The acronyms/abbreviations should be official.
<area>
- is the geographic or logical division needed to further
localize and subdivide. Examples are {Sec01, Top, End, ...}
<type>
- is the type of element, one of {HV, LV, ROM, Water, Rack, ...}
These are things which are naturally `collected' by
specialists, both within and across subsystems. The
acronyms/abbreviations are not official, but should
be obvious to all, and uniform.
<dev>
- is the `device' itself, taken loosely. Possible candidates
are {PS, Valve, Pump, Fan, GLink, ...}. When sharing of
code and templates across subsystems is anticipated, names
should be uniform.
<quant>
- is used to distinguish different quantities (attributes)
referring to the same device, such as {I, V, P, T, ...}.
Abbreviations should follow standard physics/engineering practice
for current, voltage, pressure, temperature, ...
<serial>
- is the serial number to simply enumerate repeated elements.
Typically a component name will be precisely
"<sub>:<area>:<type>
",
including the many devices which comprise it. This portion of the name should be
the most carefully chosen.
Examples:
DRC:Sec_11:HV:PS_I_99 ... Component is DRC:Sec_11:HV
EMC:End:Gas:Pump_P_88 ... Component is EMC:End:Gas
IR2:Bay_22:Rack:Fan_S_77
Miscellaneous
- Names should be unique independent of case.
- Clearly unnecessary name segments should be replaced with
"
X
".
- When both a control and monitor element refer to the set-point and
read-back of the same physical quantity, append
"
-SP
".
Abbreviations
These are required to be 3 characters long.
- Detector Subsystem Slow Controls:
-
DRC DIRC
EMC Electromagnetic Calorimeter
DCH Drift Chamber
SVT Silicon Vertext Tracker
IFR Instrumented Flux Return
- Online:
-
ODC Online Detector Control
ODF Online Data Flow
OEP Online Event Processing
OPR Online Prompt Reconstruction
ORC Online Run Control
- Other:
-
CEN Central
MAG Magnet
CRY Cryogenics
TRG Trigger
FCS Fast Control System
SFT Safety
PEP PEP-II
RAD Radiation
HER High Energy Ring
PIN PIN Diodes
This document original produced by
Steve Lewis far babar.