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

2 Outline SNL’s 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 IOC’s –DESY specific requirements

4 Loading/ Unloading SNL 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 IOC Remotely: –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 IOC’s) 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 Discussion Diagnostic: 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 IOC’s) –Special rules for what to avoid in SNL programs which need to support redundant requirements

11 SNL Manager (TODO) Remote operations Support for redundant IOC’s

12 The SNL SLAC/ DESY Connection First 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-> 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 -> make sure that all variables are updated with most recent values –Third state: fanout ->jump to the specified state

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

18 Working Plan SLAC: Debugging: –Variable Read/ Write Add New pointer to p->pvar_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 IOC’s –Exchange Load/ Start/ Stop commands between SNL Managers –Exchange values and state-set ID’s 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 it’s solved for redundant databases –Could every SNL program have it’s 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