Experimental Physics and
Industrial Control System

[email protected] · Thu, 30 Apr 2015 13:41:53 -0500

Dirk,

The system is a Windows 7 computer! Unfortunately I need this to work in
Windows because the software we use the IOC for is only Windows based.
Thank you for pointing this out since I hadn't considered it could be a
Windows compatibility issue. The ultimate goal is to use database access
to compare values at boot up with a set of stored 'good' values. I think
this will require the runtime database access routines which I've had some
success with so far. So in the end I'm hoping this might be a non issue.

Thanks again,
Doug Lormand

> I see "C:", so you work on Windows it seems. There are additional issues
> with windows and dll linkage. I guess pdbbase or any other global
> pointer has the wrong linkage. But I am not very familiar with Windows
> (and hate it). Use Linux and I bet it will work ;-)
>
> Dirk
>
> On 30.04.2015 02:27, [email protected] wrote:
>> Hello again all,
>>
>> I have been able to get the example code to work within the IOC I'm
>> trying
>> to modify, but in a round about way. It is some type of pointer problem
>> but I'm not sure what's wrong.
>>
>> So the code works if I add the following,
>>
>> void dbDumpRecords(DBBASE *pdbbase)
>> {
>>          DBENTRY *pdbentry;
>> 	long status;
>>
>> 	status =
>> dbReadDatabase(&pdbbase,"C:\\SlowControls\\EPICS\\Utilities\\Bin\\tCat.dbd",NULL,NULL);
>> 	if(!status) {printf("Database file loaded.\n");}
>> 	else {printf("Database load file failed.\n");}
>>
>> 	status =
>> dbReadDatabase(&pdbbase,"C:\\SlowControls\\EPICS\\Utilities\\Bin\\test.db",NULL,NULL);
>> 	if(!status) {printf("Records file loaded.\n\n");}
>> 	else {printf("Records load file failed.\n\n");}
>>
>>          pdbentry = dbAllocEntry(pdbbase);
>> .......rest of dump routine
>>
>> So the dump routine runs perfectly if I include dbReadDatabase routines
>> for both the database.dbd and records.db files.
>>
>> What I don't understand is why I need to Read the databases into the
>> function separately from the IOCs initialization. I thought I could
>> access
>> the runtime database in memory through pdbbase.
>>
>> So does anyone know how to access the runtime database that is loaded at
>> IOC initialization using the command DbLoadRecords? If so how can I do
>> this?
>>
>> I'm really hoping this is some easy pointer issue I'm missing due to
>> inexperience.
>>
>> Thank you,
>> Doug Lormand
>>
>>> Hello Doug,
>>> Access violation reading location 0x00000031.
>>> This looks like a NULL pointer problem. Check pdbbase and pdbentry.
>>> Dirk
>>> On 14.04.2015 01:15, [email protected] wrote:
>>>> Hello,
>>>> I am trying to use the dbDumpRecords example given in section 14.16.2
>> to
>>>> display a list of records and their fields at IOC initialization. I
>> included the example code as a function in the main.c code. Actually,
>> the
>>>> main.c has also been modified and is now called iocMain.cpp. I am
>>>> calling
>>>> the dbDumpRecords function using *iocshPpdbbase.
>>>> The example code I'm using,
>>>> ****************************************************
>>>> void dbDumpRecords(DBBASE *pdbbase)
>>>> {
>>>>       DBENTRY  *pdbentry;
>>>>       long  status;
>>>>       pdbentry = dbAllocEntry(pdbbase);
>>>>       status = dbFirstRecordType(pdbentry);
>>>>       if(status) {printf("No record descriptions\n");return;}
>>>>       while(!status) {
>>>>           printf("record type: %s",dbGetRecordTypeName(pdbentry));
>> status = dbFirstRecord(pdbentry);
>>>>           if(status) printf("  No Records\n");
>>>>           while(!status) {
>>>>               if (dbIsAlias(pdbentry)
>>>>                   printf("\n  Alias:%s\n",dbGetRecordName(pdbentry));
>>>>               else {
>>>>                   printf("\n  Record:%s\n",dbGetRecordName(pdbentry));
>> status = dbFirstField(pdbentry,TRUE);
>>>>                       if(status) printf("    No Fields\n");
>>>>                   while(!status) {
>>>>                       printf("    %s: %s",dbGetFieldName(pdbentry),
>>>>                           dbGetString(pdbentry));
>>>>                       status=dbNextField(pdbentry,TRUE);
>>>>                   }
>>>>               }
>>>>               status = dbNextRecord(pdbentry);
>>>>           }
>>>>           status = dbNextRecordType(pdbentry);
>>>>       }
>>>>       printf("End of all Records\n");
>>>>       dbFreeEntry(pdbentry);
>>>> }
>>>> **************************************************
>>>> This modification is running on a 32 bit Windows 7 machine using EPICS
>> base 3.14.12.3. The compiler is MS Visual Studio 11.
>>>> The code solution compiles without any issues but when I try to run
>>>> the
>> IOC it causes the following
>>>> Unhandled exception at 0x5C6F1C6E (dbStaticHost.dll) in tcIoc.exe:
>> 0xC0000005: Access violation reading location 0x00000031.
>>>> I have also tried several of the other static database functions,
>> dbDumpRecord, dbDumpRecordType, dbDumpMenu, and I have discovered the
>> following.
>>>> I can use the static database functions to display the record type
>>>> names,
>>>> the record names, and the record fields. But if I try to access the
>>>> record
>>>> fields the IOC will crash. If I use the dbVerify function to test the
>> record field values I get a bunch of null and not valid output, for
>> example,
>>>> Record type: ai
>>>>      Record: test1
>>>>       DESC:  (null)
>>>>       ASG:  (null)
>>>>       SCAN:  Not a valid menu choice
>>>>       PINI:  Not a valid menu choice
>>>>       PHAS:  not an integer number
>>>> etc.
>>>> Also, the
>>>> void dbDumpRecord(DBBASE *pdbbase,char *precordTypeName,int level);
>> function fails with the same type of access violation when I have tried
>> using it. All functions that try to read the record fields fail.
>> However,
>>>> if I comment out the offending function calls and start the IOC shell,
>> I
>>>> can use dbDumpRecord(pdbbase) at the prompt and it succeeds.
>>>> I am a newbie at modifying IOCs so I'm not sure what could be going
>>>> wrong
>>>> when trying to access the records fields. Any help is greatly
>>>> appreciated.
>>>> If I can post any follow up info please let me know.
>>>> Thank you in advance,
>>>> Doug Lormand
>>
>>
>>
>>
>
>

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System