Re: pvPut error message by Sequencer

[Ralph Lange <ralph.lange@gmx.de>]

On Tue, Jan 30, 2018 at 4:15 PM, Benjamin Franksen <benjamin.franksen@helmholtz-berlin.de> wrote:

On 01/30/2018 03:31 PM, Simon Reiter wrote:
> after updating from EPICS 3.14.12.6 to 3.16.1 I receive the following
> message.
> A PV is set by the sequencer (2.2.4). It is actually done, but every
> time, the sequencer set the PV, I get this message.
>
>     sevr=minor ca_array_put(typeToCA(type), count, var->chid, value):
> Channel write request failed
>
> int pv_variable;
> assign pv_variable to "{IOC}:timeout:S";
> pv_variable = value;
> pvPut(pv_variable);
>
> The connected PV is binary output.

From looking at the CA sources it seems that this is ECA_PUTFAIL error
code, which is used as the default (catch-all) error code in
src/ca/client/oldChannelNotify.cpp e.g. line 525:

    catch ( ... )
    {
        caStatus = ECA_PUTFAIL;
    }

So we know that /something/ fails and it is not any of the expected
exceptions (cacChannel::badString, ... std::bad_alloc). You could insert
debug statements in the catch-all clause to print more information about
the exception.

Does a caput from the command line work also result in an error message?

Uh-oh,

There is a (mostly harmless) bug in 3.16.1 that returns failure codes to CA put operations even if they succeed.

The underlying problem has been fixed upstream, and will be released with 3.16.2.

Meanwhile, please refer to the Known Problems page (https://epics.anl.gov/base/R3-16/1-docs/KnownProblems.html) that contains a patch.

Sorry for the inconvenience,

~Ralph