Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Fri, 19 Dec 2008 18:17:13 -0700

> ctx="read failed"
>
> I will admit that the error
> message leaves a lot to be desired though

As I recall the issues there were twofold.

1) The need to map from dbr_xxxx function error code space to ECA_XXX error code space, or an option in the protocol to pass back an error context string when there is a failure.

2) I also seem to recall, vaguely, that this particular db_get_field function didnât return a range of error codes worth mapping to ECA_XXX error code space, but perhaps this has changed or my memory isnât sufficiently clear.

I am in the midst of other tasks at the moment, but I should create a mantis entry so that this can be addressed in the future.

Jeff

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> On Behalf Of Andrew Johnson
> Sent: Friday, December 19, 2008 4:23 PM
> To: [email protected]
> Subject: Re: Units request for stringin records
> 
> Hi John,
> 
> On Friday 19 December 2008 John Faucett wrote:
> > The stringin record for EPICS 3.13.7 does not respond to a request
> > for units (DBR_GR_SHORT).
> 
> > and then realized that 3.13.7 is the version of the client
> > application.   The IOC is running 3.13.4.
> 
> > After 3 seconds the request times out with
> >
> > CA.Client.Exception...............................................
> >      Warning: "Channel read request failed"
> >      Context: "op=0, channel=ABCDE, type=DBR_GR_SHORT, count=1,
> > ctx="read failed""
> >      Source File: ../getCopy.cpp line 82
> >      Current Time: Mon Dec 19 2008 14:22:41.375447000
> > ..................................................................
> 
> Your version number for the CA client still doesn't make sense, I think you
> mean 3.14.7.
> 
> I just tried the following with 3.14.10 versions of the IOC and caget
> program,
> which works just fine as long as the VAL field contains something that can
> be
> converted into a short:
> 
> tux% caget -d DBR_GR_SHORT mrk:stringinsyn
> mrk:stringinsyn
>     Data type:      DBR_GR_SHORT (native: DBF_STRING)
>     Element count:  1
>     Value:           3
>     Status:         NO_ALARM
>     Severity:       NO_ALARM
>     Units:
>     Lo disp limit:         0
>     Hi disp limit:         0
>     Lo alarm limit:        0
>     Lo warn limit:         0
>     Hi warn limit:         0
>     Hi alarm limit:        0
> 
> However it I make the VAL field something non-numeric, I get your error
> message:
> 
> tux% caput mrk:stringinsyn abcd
> Old : mrk:stringinsyn                3
> New : mrk:stringinsyn                abcd
> tux% caget -d DBR_GR_SHORT mrk:stringinsyn
> CA.Client.Exception...............................................
>     Warning: "Channel read request failed"
>     Context: "op=0, channel=mrk:stringinsyn, type=DBR_GR_SHORT, count=1,
> ctx="read failed""
>     Source File: ../getCopy.cpp line 86
>     Current Time: Fri Dec 19 2008 17:10:15.490387940
> ..................................................................
> Read operation timed out: some PV data was not read.
> mrk:stringinsyn
>     Data type:      DBR_GR_SHORT (native: DBF_STRING)
>     Element count:  1
>     Value:           0
>     Status:         NO_ALARM
>     Severity:       NO_ALARM
>     Units:
>     Lo disp limit:         0
>     Hi disp limit:         0
>     Lo alarm limit:        0
>     Lo warn limit:         0
>     Hi warn limit:         0
>     Hi alarm limit:        0
> 
> That this fails is quite reasonable since I'm asking the IOC to convert the
> string "abcd" into an integer; the issue is nothing to do with the fact
> that
> the stringin record doesn't support units.  I will admit that the error
> message leaves a lot to be desired though; please complain to Jeff Hill
> about
> that, it's his code generating the string.
> 
> Merry Christmas,
> 
> - Andrew
> --
> The best FOSS code is written to be read by other humans -- Harold Welte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System