Use of a Relational Database at Leda

1
Use of a Relational Database at Leda

• Bob Dalesio 11-27-98

2
Previous Approach

• Wiring diagrams in Access (RDB)
• Database in Capfast

3
Capfast Vs. RDB

• Capfast
• Graphical View of data
• Hierarchical creation/viewing
• Drawing to make relationships

• RDB
• Easy tabular report generation
• Arbitrary Query Capability
• Table entry to configure

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Capfast Discussion

• Capfast is a very easy tool to use to define
  hierarchical systems - subsystem, devices,
  components.
• Capfast uses lines to depict relationships
  between these elements (these show record
  processing and data flow very intuitively)
• Many instances of the components can be created
  with only one copy of the template - which can
  be modified at any time - changing all instances
• Fields like DTYP, LINR, EGUF, EGUL, ZNAM, ONAM
  are all in property sheets that must be opened to
  modify them
• Changes to these fields require selecting each
  property to modify
• Arbitrary reports are not possible - unless the
  ASCII report is fed into a relational database
  (we have a prototype tool operational to do this)

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RDB Discussion

• An RDB provides very versatile report generation
  capability
• Data entry is particularly easy - particularly
  for entering the same value into many records at
  the same time
• The ability to order the report based on any
  field makes the verification of hardware
  addresses and the checking of name spelling
  particularly simple
• It is very difficult to see complex EPICS record
  relationships by following the text entries in an
  RDB
• Data and processing links would be more difficult
  to enter as names would need to be spelled
  properly (where Capfast only requires a wire)

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LEDA Vacuum System Approach

• Use Capfast to create the hierarchical
  description of the database - subsystem, device,
  component, signals
• Use Capfast to configure the process flow and
  data flow - making all SCAN, FLNK, soft INP/OUT,
  NPP/PP, CALC, and HIGH for BO visible on the
  schematic.
• From the Capfast produced database - create an
  Access database
• In Access - enter configuration fields hw
  INP/OUT, LINR, DTYP, EGUF, EUGL, ZNAM, ONAM etc.
• Load the database from Capfast then the database
  from Access - EPICS will create records if there
  is no existing record - or overwrite any fields
  in the last loaded database

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Results

• Capfast database was defined by the project
  engineer
• RDB parameters were entered by a technician
• Reports generated for signal checkout from Access
  expedited the process
• Changes required to classes of channels for
  labels, hardware type and engineering units could
  be done to 10s or hundreds of records in seconds
• Loading two databases slows the reboot time by
  about 10 seconds.
• Having the source in two places requires more
  coordination.
• Deleting or changing the names of existing
  records was the most difficult operation - it
  required locating and deleting the records in
  Access
• The inconvenience for deleting records was more
  than compensated for by the ease of channel check
  out and ability to reconfigure many channels at
  once. The schematics are still the easiest way to
  understand a database.