Experimental Physics and
Industrial Control System

Heinz Junkes <[email protected]> · Tue, 14 Aug 2018 18:12:10 +0200

I have a question about bitSets.

I use the example program from exampleCPP get.cpp
with the code fragment

        PvaClientGetDataPtr data = pvaClientGet->getData();
        BitSetPtr bitSet =  data->getChangedBitSet();

Cardinality is "1" although obviously nothing changes.
Bit #0 is set “structure”.

Now to my question. Is bitSet set by the server?

And then I don't understand that either (from the documentation).

"Only fields that change are transmitted.
Only the data for fields that change value between requests are sent.”

in the pvaGet I only request “value”.

The PV I am looking at is a classic V3 PV (ca) and on my server runs pvAccess-Server (qsrv).

ioc:

dbpr CRYAFM:AWG0:DDSA:SetDDSFreq,4

ACKS: NO_ALARM      ACKT: YES           ADEL: 0             ALST: 123456        
AOFF: 0             ASG:                ASLO: 0             ASP: 0x0            
BKLNK: 00 00 00 00 00 00 00 00 00 00 00 00                  BKPT: 00            
DESC: Frequency DDS DDSA:               DISA: 0             DISP: 0             
DISS: NO_ALARM      DISV: 1             DOL:CONSTANT        DPVT: 0x19df880     
DRVH: 0             DRVL: 0             DSET: 0x4fb724      DTYP: asynFloat64   
EGU: Hz             EGUF: 0             EGUL: 0             EOFF: 0             
ESLO: 1             EVNT:               FLNK:CONSTANT 0     HHSV: NO_ALARM      
HIGH: 0             HIHI: 0             HOPR: 0             HSV: NO_ALARM       
HYST: 0             INIT: 0             IVOA: Continue normally                 
IVOV: 0             LALM: 123456        LBRK: 0             LCNT: 0             
LINR: NO CONVERSION LLSV: NO_ALARM      LOLO: 0             LOPR: 0             
LOW: 0              LSET: 0x1942808     LSV: NO_ALARM       MDEL: 0             
MLIS: 00 00 00 00 00 00 00 00 00 00 00 00                   MLOK: 01 94 e7 40   
MLST: 123456        NAME: CRYAFM:AWG0:DDSA:SetDDSFreq       NSEV: NO_ALARM      
NSTA: NO_ALARM      OIF: Full           OLDSIMM: NO         OMOD: 0             
OMSL: supervisory   ORAW: 123456        ORBV: 0             OROC: 0             
OUT:INST_IO @asyn(awg0, 0)DDS Frequency OVAL: 123456        PACT: 0             
PBRK: 0x0           PHAS: 0             PINI: NO            PPN: 0x0            
PPNR: 0x0           PREC: 3             PRIO: LOW           PROC: 0             
PUTF: 0             PVAL: 123456        RBV: 0              RDES: 0xcdc5d0      
ROFF: 0             RPRO: 0             RSET: 0x4fbac8      RVAL: 123456        
SCAN: Passive       SDIS:CONSTANT       SDLY: -1            SEVR: NO_ALARM      
SIML:CONSTANT       SIMM: NO            SIMPVT: 0x0         SIMS: NO_ALARM      
SIOL:CONSTANT       SPVT: 0x0           SSCN: <nil>         STAT: NO_ALARM      
TIME: 2018-08-14 08:51:37.697697041     TPRO: 0             TSE: 0              
TSEL:CONSTANT       UDF: 0              UDFS: INVALID       VAL: 123456         

humma-kavula:examples junkes$ cainfo CRYAFM:AWG0:DDSA:SetDDSFreq
CRYAFM:AWG0:DDSA:SetDDSFreq
    State:            connected
    Host:             cry-test.rz-berlin.mpg.de:5064
    Access:           read, write
    Native data type: DBF_DOUBLE
    Request type:     DBR_DOUBLE
    Element count:    1

humma-kavula:examples junkes$ pvinfo CRYAFM:AWG0:DDSA:SetDDSFreq
CHANNEL  : CRYAFM:AWG0:DDSA:SetDDSFreq
STATE    : CONNECTED
ADDRESS  : 141.14.128.53:5075
epics:nt/NTScalar:1.0
    double value
    alarm_t alarm
        int severity
        int status
        string message
    time_t timeStamp
        long secondsPastEpoch
        int nanoseconds
        int userTag
    display_t display
        double limitLow
        double limitHigh
        string description
        string format
        string units
    control_t control
        double limitLow
        double limitHigh
        double minStep
    valueAlarm_t valueAlarm
        boolean active
        double lowAlarmLimit
        double lowWarningLimit
        double highWarningLimit
        double highAlarmLimit
        int lowAlarmSeverity
        int lowWarningSeverity
        int highWarningSeverity
        int highAlarmSeverity
        double hysteresis

get, nothing is changing ???

code fragment:

   void get()
    {

        if(!channelConnected) {
            cout << channelName << " channel not connected\n";
            return;
        }
        if(!getConnected) {
            cout << channelName << " channelGet not connected\n";
            return;
        }
        pvaClientGet->get();
        PvaClientGetDataPtr data = pvaClientGet->getData();
        BitSetPtr bitSet =  data->getChangedBitSet();
cout << "bitset Cardinality : " << bitSet->cardinality() << endl;
        if(bitSet->cardinality()>0) {
             cout << "changed " << channelName << endl;
             data->showChanged(cout);
             cout << "bitSet " << *bitSet << endl;
        }
    }

output:

channelGetConnect CRYAFM:AWG0:DDSA:SetDDSFreq status Status [type=OK]
channelGetDone CRYAFM:AWG0:DDSA:SetDDSFreq status Status [type=OK]
bitset Cardinality : 1
changed CRYAFM:AWG0:DDSA:SetDDSFreq
 = epics:nt/NTScalar:1.0 
    double value 123456
    alarm_t alarm
        int severity 0
        int status 0
        string message NO_ALARM
    time_t timeStamp
        long secondsPastEpoch 1534254697
        int nanoseconds 697697041
        int userTag 0
    display_t display
        double limitLow 0
        double limitHigh 0
        string description Frequency DDS DDSA:
        string format 
        string units Hz
    control_t control
        double limitLow 0
        double limitHigh 0
        double minStep 0
    valueAlarm_t valueAlarm
        boolean active false
        double lowAlarmLimit nan
        double lowWarningLimit nan
        double highWarningLimit nan
        double highAlarmLimit nan
        int lowAlarmSeverity 0
        int lowWarningSeverity 0
        int highWarningSeverity 0
        int highAlarmSeverity 0
        double hysteresis 0

bitSet {0}

channelGetDone CRYAFM:AWG0:DDSA:SetDDSFreq status Status [type=OK]
bitset Cardinality : 1
changed CRYAFM:AWG0:DDSA:SetDDSFreq
 = epics:nt/NTScalar:1.0 
    double value 123456
    alarm_t alarm
        int severity 0
        int status 0
        string message NO_ALARM
    time_t timeStamp
        long secondsPastEpoch 1534254697
        int nanoseconds 697697041
        int userTag 0
    display_t display
        double limitLow 0
        double limitHigh 0
        string description Frequency DDS DDSA:
        string format 
        string units Hz
    control_t control
        double limitLow 0
        double limitHigh 0
        double minStep 0
    valueAlarm_t valueAlarm
        boolean active false
        double lowAlarmLimit nan
        double lowWarningLimit nan
        double highWarningLimit nan
        double highAlarmLimit nan
        int lowAlarmSeverity 0
        int lowWarningSeverity 0
        int highWarningSeverity 0
        int highAlarmSeverity 0
        double hysteresis 0

bitSet {0}

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System