Evolution of EPICS Core

V4 – Executive Summary

• Provide online add/delete of I/O to support continuous operation.
• Provide redundant control of remote I/O to support improved reliability.
• Provide name introspection and domain control in support of seamless *integration of large control systems
• Provide triggers, filters, and rate limits to improve resource use of network and client side processing
• Provide hierarchical devices to support higher level view of application in the front-end processors.
• Provide automatic backup and restore to support bump-less reboot and synchronization of redundant controllers.
• Provide atomic read, write, and write with read-back to multiple channels to support synchronized access of arbitrary sets of channels.
• Support international users with uni-code and time.
• Remove limitations on string lengths, device states, number of input links to support arbitrary sizes.
• Internationalize Time Stamps

V4 – Structure and Array Support

• Allows definition and access to complex devices and multi-dimensional arrays
• Name hierarchy in Channel Access
  • <arbitrary string>.structure. Element[n]
  • e.g. Arc3PwrSupply.readback.status, ArcPwrSupply.readback.value
• Device description in database
• Support arbitrary number of inputs to calculations and subroutines.
• Support multi-state devices of an arbitrary number of states

V4 – Data Acquisition Capabilities

• New subscription parameters
  • Rate limit
  • Value changes (as before but also % change)
  • Triggers
  • Filters
  • Examples
  • Send BPM at 1 Hz (where 1 Hz across IOCs is the same)
  • Send BPM when trigger specifies that this pulse is e-
  • Send RF reading when filter says that vacuum is higher than 10e-6 torr
• Allows more accurate requests for data on client applications
• Reduces the amount of network and client CPU usage
• Specify priority for circuit - QOS

V4 – Device Read/Write Operations

• Allows multiple fields to be read/written as an atomic operation
• Reads/Writes can be triggered
  • e.g. Put( Corr1.K, Corr2.K, Corr3.K, on trigger event)
  • All puts take place when the trigger event occurs
• Write with return data support (Command/Response)
• Ramping/arb function outputs – given two end points

V4 – Name Resolution Extensions

• Allow wildcard searches
• Allow request to send all names supported in the IOC
• Support redundancy by allowing connections to specify that they are not active
• Support multiple name servers by allowing connections to specify how close to the source they are.
• Name aliasing supported.

V4 – Online Add / Delete

• Support hardware address change during operation
• Allow new record instances to be loaded at any time
• Support addition of hardware of an already supported type (64x)
• Support addition of new hardware during operation.
• Remove records during operation.

V4 – Redundancy: Multiple masters of remote I/O

• Support name responses from multiple controllers of the same database.
• Support request for all fields from a primary database to its backup.
• Support a request for all fields that have changed since the last synchronization of the backup to the primary.
• Support a mechanism for switching from the primary to the backup.
• Provide a mechanism for synchronizing primary and the backup.
• Support multiple communication paths that provide
  • an isolated network for synchronization traffic
  • redundant checks to synchronize switch over behavior.
• Provide a mechanism to start/stop scanning
• Provide a mechanism to start/stop sequences
• Provide a mechanism to start/stop drivers from scanning

V4 – Support Large / Multi-segmented Control System

• Support load balancing between multiple data sources (1st order gateway, 2nd order gateway, IOC, and load).
• Support domain control independent of network topology
  • Beamline data is not available to the control room
  • Only insertion gap and beam quality information is available to the beamline controls from the ring control room.

V4 – Extendable Metadata / Properties

• Metadata can be extendable –
  • Add array dimensions
  • Add time base to an array
  • Application programmers can add metadata
• Specify metadata by field rather than record
  • Only get metadata when it is meaningful
  • No display limits for the high display limit
• Calc and subroutine records have arrays of inputs
  • No limit to the number of variables

V4 – Channel Access Diagnostics

• Server Diagnostics
  • Connections
  • Channels
  • Events per second
  • State of Health
  • Beacon Periodicity
  • Etc…
• Client Diagnostics
  • Number of connections/server per client
  • Number of channels
  • Events per second
  • State of connection
  • Etc…..

V4 – Limitations Remediation

• Multi-line text
• Variable length strings
  • Removes current limitations of 40 characters
  • Reduces size of memory use in most cases
  • Reduces network traffic in most cases
• Unicode
  • Support alternate character sets
• Multidimensional arrays
• Variable size arrays

V4 – Time Stamp Internationalization

• Support ISO 8601 Format
  • Year-month-date-hours-minutes-seconds-fractional seconds
  • Country specific time stamps
• Support Locale Settings for conversions
  • ,02 as 2 hundreds of a second

V???? – Resource Consumption Quotas

• User specific CA client resource consumption quotas in access security system