Re: dbpf before iocInit...

[Ralph Lange <Ralph.Lange@bessy.de>]

Hi Emmanuel,
It's probably even much simpler than that.

As you found out, dbpf() is part of the *runtime database access 
library*, which works only at runtime (properly locking the record to 
avoid interfering with the regular processing of records). As the locks 
are set up during IOCinit, using dbpf() at database load time will fail.

If you want to change field values of records before IOCinit, nothing 
keeps you from setting the additional fields in the plain regular 
fashion from a db file that gets instantiated in a later call to 
dbLoadRecords(). It is perfectly legal to have the same record appear in 
more than one instantiation step. (It might not be explicitly mentioned 
in the doc that this is legal, but I learned that many installations use 
this feature.)

Let me give you an example:

You may load a record in first.db like this:
record(ai,"record1") {
  field(DOL,".5")
}

and then overwrite/add fields in second.db (which is loaded further down):
record(ai,"record2") {
  ...
}
record(ai,"record1") {
  field(DOL,"300")
  field(FLNK,"record2")
}

Most simple, obvious, straightforward, exactly what you want.

On-line adding and deleting records (after IOCinit) is not an easy thing 
to do and not supported at the moment. It has been on wish lists for a 
while and might get implemented in the next major version of EPICS. Call 
again in two years ... ;-)

Cheers,
Ralph


Allison, Stephanie wrote:

> Hi,
>
>  
>
> > So, immediately in the block/template instanciate(record2), I 
> > insert dbpf("record1.FLNK","record2").
> >    
> Part of our IOC startup is to restore values before iocInit using static database utilities.  I don't know of any iocsh entries for dbStatic routines.  You can write a little utility that does something like this:
>
> #include "dbAccess.h"
> #include "dbStaticLib.h"
> #include "errlog.h"
>
> 	long dbpfStatic(char   *pname,char *pvalue) {
> 	DBENTRY         dbentry;  
> 	int             status;	
> 	if (!pdbbase) {
> 		errlogPrintf("dbpfStatic: No database loaded\n");
> 		return -1;
> 	}
> 	dbInitEntry(pdbbase, &dbentry);	 
> 	if (!(status = dbFindRecord(&dbentry, pname))) 
> 		status = dbPutString(&dbentry, pvalue);
> 	dbFinishEntry(&dbentry);
> 	return status;
> 	}
>
> Stephanie Allison
>