Re: seq pvPut to a waveform

[Ben Franksen <ben.franksen@online.de>]

On Samstag, 2. Oktober 2010, Dayle Kotturi wrote:
> I'd be grateful for code snippets showing how to put a waveform of
> values to a PV. I am able to successfully pvPut other data types, but
> just not waveforms. I've tried to match the sytax of caput -a where
> the first arg is NELM (or NORD) and then the array is appended after
> that.  

No, this is just caput command line syntax. Just pvPut the array of 
values.

> I've also tried just puttting the array of NELM values. 
> Neither worked.  

It should. But see below for a possible reason why your program does not 
work.

> No error messages on the console with +d option set. 
> Recompiling seq-R2-0-11 with DEBUG defined caused a segmentation
> fault. I didn't investigate the reason for that.

Not necessary, I already fixed this a while ago in the development 
version. Seems nobody tried to compile with DEBUG for a long time...

> Versions: epics3.14.8.2 and seq-R2-0-11
> Platform: linux-x86
>
> Details: I have a waveform of 21 shorts that I want to put to a PV of
> FTVL USHORT with NELM 21.
>
> [cdlx08] /afs/slac/g/lcls/tools/script>caget KLYS:LI20:95:RULE0
> KLYS:LI20:95:RULE0 21 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0
>
> On the (soft) ioc:
> epics> dbpr("KLYS:LI20:95:RULE0",4)
> ACKS: NO_ALARM      ACKT: YES           ASG:                ASP:
> 0x00000000 BKPT: 0x00          BPTR: 0x483eef09    BUSY: 0           
>  DESC: Rule DISA: 0             DISP: 0             DISS: NO_ALARM   
>   DISV: 1 DPVT: 0x00000000    DSET: 0xfc578000    DTYP: Soft Channel 
> EGU: tick EVNT: 0             FLNK:CONSTANT 0     FTVL: USHORT       
> HOPR: 0 INP:CONSTANT        LCNT: 0             LOPR: 0            
> LSET: 0xc06cf309 MLIS: 0x98adf80988a9f80902000000        MLOK:
> 0x303eef09
> NAME: KLYS:LI20:95:RULE0                NELM: 21            NORD: 21
> NSEV: NO_ALARM      NSTA: NO_ALARM      PACT: 0             PHAS: 0
> PINI: YES           PPN: 0x00000000     PPNR: 0x00000000    PREC: 0
> PRIO: LOW           PROC: 0             PUTF: 0             RARM: 0
> RDES: 0x20a6e009    RPRO: 0             RSET: 0x203ed800    SCAN:
> Passive SDIS:CONSTANT       SEVR: NO_ALARM      SIML:CONSTANT      
> SIMM: NO SIMS: NO_ALARM      SIOL:CONSTANT       SPVT: 0x00000000   
> STAT: NO_ALARM TIME: 0x0cd6072760513f19                TPRO: 0       
>      TSE: 0 TSEL:CONSTANT       UDF: 0              VAL: 0x00000000
>
> at top before start of state set:
> option -a; /* sync op. wait for pvGet/pvPut to complete */
> option -c; /* no wait for db connections */
> option +d; /* Turn on runtime debug messages */
> option +w; /* Display SNC warnings */
>
> #define PDU_RULE_PUT_WF_SIZE 22 /* includes 1 for the NELM */
>
> /* Tempory variable re-used to hold the trigger rule copied from an
>     updated global rule and assigned to an RTEMS IOC trigger rule
> that uses it */ short myTriggerRule[PDU_RULE_PUT_WF_SIZE];
> assign myTriggerRule to ""; /* MUST do this to get this var into DB
> Block per Kuhkee Kim 2010/09/30 */
>
> /* Inside a state */
>              pvAssign(myTriggerRule,"KLYS:LI20:95:RULE0");
>              pvMonitor(myTriggerRule);

At this point, i.e. before calling pvPut, you must first ensure that 
myTriggerRule has connected to the assigned PV: connecting to a PV is 
an asynchronous operation. This can be done by jumping to an additional 
state:

state wait_connect_myTriggerRule {
  when (pvConnected(myTriggerRule)) {
    pvPut(myTriggerRule);
    ... etc. ...
  }
}

>              /* Update the definition of the trigger rule to match
> the global rule it is assigned to */
>              pvPut(myTriggerRule);
>              pvFlush();
>              printf("sncpdu: contents of SNL var now put into EPICS
> PV\n");
>
>              sprintf(pvNORD, "%s.NORD",triggerRuleStrings[nn]);
>              pvAssign(myTriggerRuleNORD,pvNORD);

It is not necessary nor makes sense to write to NORD, as this field is 
updated by the record support put_array_info method which is called 
whenever VAL gets written to (e.g. via CA).

Cheers
Ben