Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 19 Dec 2008 17:22:49 -0600

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