Re: How can I get the severity fields values for a limit alarm?

["Kasemir, Kay via Tech-talk" <tech-talk@aps.anl.gov>]

Hi:

> I am developing a CA client program in C and I need to handle the severity value for the alarm limits (HIHI, HIGH, LOW, LOLO). This is, the value of HHSV, HSV, LSV and LLSV fields.

Note that there's a difference between what you see via channel access, and records.

If you are developing a CA client program, you're best doing just that, because there may not be any records.

From the CA client perspective, you get the DBR_STS_xxx data type which will provide you with the value, alarm status and severity.

If the channel is associated with a record, specifically an analog record, then yes, a MAJOR alarm could indicate that VAL >= HIHI and HHSV = MAJOR.

In that case, you could try to read name_of_record.HIHI, but the channel could also be served by PCASPY or some other CAS-based server, and in that case there is no record, and nobody will respond to a read request for name_of_record.HIHI. Same with HHSV.

From the CA client perspective, you instead need to get the DBR_CTRL_xxx data type which has the alarm threshold values.

-Kay

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From: tech-talk-bounces@aps.anl.gov <tech-talk-bounces@aps.anl.gov> on behalf of rperez via Tech-talk <tech-talk@aps.anl.gov>
Sent: Thursday, January 17, 2019 7:55 AM
To: tech-talk@aps.anl.gov
Subject: How can I get the severity fields values for a limit alarm?

 

Hello,

I am developing a CA client program in C and I need to handle the severity value for the alarm limits (HIHI, HIGH, LOW, LOLO). This is, the value of HHSV, HSV, LSV and LLSV fields.

To do this, I am executing the following code:

    struct dbr_ctrl_double    tPvData;
    double data;
    chid    mychid;

    SEVCHK(ca_context_create(ca_disable_preemptive_callback),"ca_context_create");
    SEVCHK(ca_create_channel("PC:MEM_USED",NULL,NULL,10,&mychid),"ca_create_channel failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");

    SEVCHK(ca_get(DBR_DOUBLE,mychid,(void *)&tPvData),"ca_get failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");

     printf("PV Name %s :\n \talarm status: %d\n \talarm severity: %d\n \tvalue: %f\n \tunits: %s\n \talarm limits: [%d-%d]\n \twarning limits: [%d-%d]\n",
                               "PC:MEM_USED",  tPvData.status, tPvData.severity, tPvData.value, data.units,
                                tPvData.lower_alarm_limit, tPvData.upper_alarm_limit,
                                tPvData.lower_warning_limit, tPvData.upper_warning_limit);

    SEVCHK(ca_get(DBR_DOUBLE,mychid,(void *)&data),"ca_get failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    printf("PV Name %s=%f\n","PC:MEM_USED", data);

    return(0);

As result I get the following PV's data, even the alarm (HIHI, LOLO) and warning (HI, LO) limits.

PV Name PC:MEM_USED  :
     alarm status: 3
     alarm severity: 2
     value: 100.000000
     units: %
     alarm limits: [nan-95.000000]
     warning limits: [nan-85.000000]

     PV Name PC:MEM_USED =100.000000

But to get the HHSV, HSV, LSV and LLSV fields, I am doing the following:

    SEVCHK(ca_create_channel("PC:MEM_USED.HHSV",NULL,NULL,10,&mychid),"ca_create_channel failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    SEVCHK(ca_get(DBR_DOUBLE,mychid,(void *)&data),"ca_get failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    printf("%s= %f\n","PC:MEM_USED.HHSV",data);

    SEVCHK(ca_create_channel("PC:MEM_USED.HSV",NULL,NULL,10,&mychid),"ca_create_channel failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    SEVCHK(ca_get(DBR_DOUBLE,mychid,(void *)&data),"ca_get failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    printf("%s= %f\n","PC:MEM_USED.HSV",data);

    SEVCHK(ca_create_channel("PC:MEM_USED.LLSV",NULL,NULL,10,&mychid),"ca_create_channel failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    SEVCHK(ca_get(DBR_DOUBLE,mychid,(void *)&data),"ca_get failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    printf("%s= %f\n","PC:MEM_USED.LLSV",data);

    SEVCHK(ca_create_channel("PC:MEM_USED.LSV",NULL,NULL,10,&mychid),"ca_create_channel failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    SEVCHK(ca_get(DBR_DOUBLE,mychid,(void *)&data),"ca_get failure");
    SEVCHK(ca_pend_io(5.0),"ca_pend_io failure");
    printf("%s=%f\n","PC:MEM_USED.LSV",data);

As result, I am getting this:

     "PC:MEM_USED.HHSV=2.000000" which means severity for a Hihi alarm is MAJOR

     "PC:MEM_USED.HSV=1.000000" which means severity for a Hi alarm is MINOR

     "PC:MEM_USED.LLSV=0.000000" which means severity for a Lolo alarm is NO_ALARM

     "PC:MEM_USED.LSV=0.000000" which means severity for a Lo alarm is NO_ALARM

Taking this into account, I have the following doubts:

1. Is the value of the alarm severity  filed = 2 (MAJOR ) derived from this HHSV alarm severity limit field?  or is it only a coincidence that the value of the alarm severity is also 2 (MAJOR)? If so, what is the difference between the alarm severity field and the severity for a Hihi alarm field (HHSV)?

2. Is this the correct way ( this is executing ca_get (PC:MEM_USED.HHSV), etc...) to obtain these HHSV, HSV, LLSV and LSV values?  Is there any other simpler way?

Thank you very much in advance.