SNL

1
SNL

• Current State(in transition state)
• By
• Matthias Clausen
• Ron Chestnut

2
Outline

• SNLs home
• Wish list
• Results of the 1st phase of the design discussion
• Work breakdown table
• Points of interest for the next phase

3
SNL Development

• SNL is currently supported and developed by SLAC
• The following list will show requirements which
  are driven by
• The EPICS community
• New EPICS V4 features
• Special features for redundant IOCs
• DESY specific requirements

4
Loading/ UnloadingSNL Programs

• Configuration utility to take care of the images
  loaded to the IOC during boot
• startup.SNL configuration
• Utility program to remotely load new programs
  without logging on to the IOCRemotely
• Loading programs
• Starting programs (with configuration file)
• Stopping programs
• Unloading programs

5
SNL Startup

• Coldstart
• Start programs from startup.SNL
• Start programs local/ remote without
  configuration file
• Warmstart
• Start list of programs with individual
  configuration file
• Configuration file may only contain
  startup-states
• Redundant Start
• Start list of programs with individual
  configuration file
• Configuration file could be memory resident in
  the SNL executive (streamed in from the SNL exec.
  of the current master of a redundant pair of
  IOCs)
• Configuration file contains startup-states and
  the values of local variables (incl. timers)

6
Diagnostic

• Needs a well defined network protocol(TBD)
• Get list of loaded programs
• Loaded but not running (how?)
• Loaded and running (all instances like seqShow)
• For a selected program instance
• State of all state sets like seqShow name
• Values of all variables, timers etc., records
• Debugging
• Change value of variables/ timer etc.
• Change current state to another/ next
  state(choice list introspected from the running
  state set)
• Single step through the SNL programs

7
SNL Manager

• Provides remote operation/ activation of SNL
  programs
• Provides diagnostic information
• Extracts current runtime status/states from
  SNL-runtime on the Master IOC to the Slave IOC
  (protocol undefined)
• Accepts configuration data from Master IOC.
• Can be set to Master/ Slave mode by
  Redundancy-Executive

8
On the wish list

• Graphical SNL design tool
• Interactive/ graphical debugger

9
Current State of DiscussionDiagnostic

• CA might be the right protocol to get diagnostic
  information
• A local CA-Server in the SNL-runtime manager
  would allow
• To dynamically add/ delete records which
  represent the running SNL programs
• Special SNL records could be used to
• keep all information about an individual state
  set
• States (and possible transition states)
• Variables and their values
• Send commands to state set
• Change value of variable
• Goto state (from given list of states)
• Single step in state program

10
SNL Style Guide (TODO)

• Whenever possible
• SNL programs can be started from
  beginning(Runtime flag will indicate whether
  programs must be synchronized between redundant
  IOCs)
• Special rules for what to avoid in SNL programs
  which need to support redundant requirements

11
SNL Manager (TODO)

• Remote operations
• Support for redundant IOCs

12
The SNLSLAC/ DESY ConnectionFirst Design Ideas

• Results of a first discussion
• SNL Manager will be the key application to
  provide most of the required functionality

13
SNL Manager

• Contains extended SEQ Library
• Provides interface to all internals
• From command line
• Through network interface (tbd)
• Loads programs
• Start programs with configuration data
• Set values of internal variables ( from )
• Stops programs

14
SNL Manager

• Redundant Links
• Send updates to Slave processor
• Load/ start/ stop/ unload programs
• Change of state
• Change of variables
• Receive updates from Master and execute
• Connector to Executive
• Set to Master/ Slave

15
SNL Manager

• Debug Mode Through SEQ Library (can possibly be
  done for 3.14.x)
• Access to internal variables
• Read/ Write
• New pointer pvar_desc-gt array of (name, type,
  offset in pvar)
• Force state transition
• Hidden piece in each when clause
• Only legal transitions are possible
• Single state stepping
• Hidden piece in each when clause
• Single SNL statement stepping
• TBD

16
SNL Startup

• Programs written according to SNL Style guide.
• First state Wait until selected
• Second state init -gt make sure that all
  variables are updated with most recent values
• Third state fanout -gtjump to the specified state

17
SNL Manager
Command line Interface
Network Interface Incl. Load/ Start/ Stop
Link Interface
SEQ Library
Executive
SLAC DESY
18
Working Plan

• SLAC
• Debugging
• Variable Read/ Write
• Add New pointer to p-gtpvar_desc
• Force state transition
• Add hidden piece in each when clause
• Single state stepping
• Add hidden piece in each when clause
• SEQ
• Make new functionality available through command
  line interface
• SNL Manager
• Integrate SEQ-Library
• Participate in Load/ Start/ Stop implementation

• DESY
• Design and develop network layer
• Access to SEQ library likewise the command line
  interface
• Participate in Load/ Start/ Stop implementation
• Link Interface for redundant IOCs
• Exchange Load/ Start/ Stop commands between SNL
  Managers
• Exchange values and state-set IDs between SNL
  Managers
• Interface to Redundancy Executive

19
Points of Interest

• Following closely what EPICS V4 will provide
• Could all the internal variables be EPICS
  records?
• All the synchronization would be given once its
  solved for redundant databases
• Could every SNL program have its own CA-Server?
• Could all variables be dynamically added to the
  virtual namespace of the IOC they are running
  on?
• Unresolved issues
• Dynamically loading new SNL programs is not
  supported on every operating system EPICS is
  currently running on