Re: Question about extracting information from a bo type record in EPICS

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Please show the complete output when you run your program.


Sent from my iPhone

> On Oct 20, 2022, at 10:32 AM, Meddage, Varuna <meddage at phys.ksu.edu> wrote:
> 
> Yes,
> 
> 
> I can compile it, and no run time error either. But I cannot extract the desired value from the PV using ca_get command.
> 
> 
> ________________________________
> From: Mark Rivers <rivers at cars.uchicago.edu>
> Sent: Thursday, October 20, 2022 10:13:00 AM
> To: Meddage, Varuna
> Cc: tech-talk at aps.anl.gov
> Subject: Re: Question about extracting information from a bo type record in EPICS
> 
> You did not tell us what the actual problem is. Does it fail to compile, or give a runtime error, or give the “wrong” result?
> 
> Mark
> 
> 
> Sent from my iPhone
> 
>> On Oct 20, 2022, at 10:06 AM, Meddage, Varuna via Tech-talk <tech-talk at aps.anl.gov> wrote:
>> 
>> Hi,
>> 
>> 
>> I have question about extracting PV value from a bo type record in EPICS through an external C++ program.
>> 
>> 
>> If I explain the issue in detail,
>> 
>> 
>> First I created a bo type record in one of the .db files. Then I was able to successfully change the value of this record using CS - studio GUI using an on/off switch. (used ca_get command to confirm whether the PV value is changed, when I toggle the on/off switch in CSS GUI)
>> 
>> 
>> ////////////////////////////////////////// This is the b0 type record in my .db file ///////////////////////
>> 
>> 
>> record(bo,"$(detector)_wib$(crate)0$(wib)_femb$(femb)/switch")
>> 
>> {
>> 
>> field(DTYP,"")
>> 
>>       field(OUT,"CA_LINK")
>> 
>>       field(SCAN,"Passive")
>> 
>>       field(DESC,"Status")
>> 
>> field(ZSV,"MAJOR")
>> 
>> field(OSV,"NO_ALARM")
>> 
>> field(ZNAM,"Off")
>> 
>> field(ONAM,"On")
>> 
>> }
>> 
>> 
>> //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
>> 
>> 
>> But when I try to extract the value of this PV through an external C++ program, using ca_get command, I cannot do that successfully.
>> 
>> 
>> 
>> /////////////////////////////////////////////////// rough outline of the C++ program used to extract PV value ///////////////
>> 
>> 
>> chid femb[N_FEMB_PV];
>> 
>> int status;
>> 
>> 
>> std::cout << "********************** FEMB sensor summmary ************************** \n";
>> 
>> 
>> 
>> for(int i=0; i<N_FEMB_PV; i++) {
>> 
>>    sprintf(femb_pv[i], femb_pv_pattern[i]);
>> 
>>    printf("%s\n", femb_pv[i]);
>> 
>>    status = ca_create_channel(femb_pv[i], NULL, NULL, 0, &femb[i]);
>> 
>>    SEVCHK(status,"ca_create_channel error");
>> 
>>    status = ca_pend_io(1.0);
>> 
>>    SEVCHK(status,"ca_pend_io error");
>> 
>> 
>> 
>>    printf("PV:    %s\n", ca_name(femb[i]));
>> 
>>    printf("State: %d\n", ca_state(femb[i]));
>> 
>>    printf("Host   %s\n", ca_host_name(femb[i]));
>> 
>>    printf("Read:  %d\n", ca_read_access(femb[i]));
>> 
>>    printf("Write: %d\n", ca_write_access(femb[i]));
>> 
>>    printf("Type:  %s\n", dbr_type_to_text(ca_field_type(femb[i])));
>> 
>>    printf("Count: %d\n", ca_element_count(femb[i]));
>> 
>>    printf("State: %d\n", ca_state(femb[i]));
>> 
>> }
>> 
>> 
>> double femb_power_commands[96];
>> 
>> 
>> for (int entry=0; entry<some_number; entry++){
>> 
>> status = ca_get(DBR_DOUBLE,femb[entry],&femb_power_commands[entry]);
>> 
>> }
>> 
>> 
>> ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
>> 
>> 
>> Any advice to solve this issue is really appreciated.
>> 
>> 
>> Thanks
>> 
>> Varuna Meddage