Experimental Physics and
Industrial Control System

Walter Werner <[email protected]> · Mon, 15 Dec 2014 15:22:48 +0100

hi Andrew

Thanks,

2014-12-12 17:44 GMT+01:00 Andrew Johnson <[email protected]>:
> Hi,
>
> On 12/12/2014 10:28 AM, Walter Werner wrote:
>> I use pyepics for my client and want to avoid the "Virtual circuit
>> disconnect" exception from CA being printed on the standard input.
>> CA.Client.Exception...............................................
>>     Warning: "Virtual circuit disconnect"
>>     Context: "localhost:20000"
>>     Source File: ../cac.cpp line 1215
>>     Current Time: Wed Dec 10 2014 05:51:45.821307011
>> ..................................................................
>> This exception accrues if the server is down.
>
> Do you have a connection callback handler for your PVs? If not,
> supplying one may prevent some of the disconnect messages (and permit
> your code to find out when it should stop trying to access the PV values).

Yes, i do have the connection handler. And i try to recoonect the pv
if the connection is lost. As far as i know the PV class does not
reconnect automatically. My problem was more a cosmetic nature for the
end user. It looks not very nice if some exception is printed on the
console, although i already take care of it.

> You can also redirect any/all error messages from the underlying CA
> library by providing your own printf handler. From the pyepics
> documentation for the low-level CA module:
>> epics.ca.replace_printf_handler(fcn=None)
>>   Replace the normal printf() output handler with the supplied
>>   function (defaults to sys.stderr.write())
>
> Note that a single message like the one you quoted above may have come
> from several calls to the printf handler routine, so don't just try to
> pop up a new dialog box every time it gets called.

that was the method i was looking for !!! The example code looks like this:

----------------
def my_printf_handler(output_str):
    pass
    #TODO write output_str to some logfile

epics.ca.replace_printf_handler(my_printf_handler)
---------------

regards
   Walter

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System