ConnectionFailed exception subscribing to a change event

# 7 years ago
jcambon	Hi, I am perhaps missing something obvious, but I am unable to subscribe a change event for some attributes. Look at the attached example, that I run on the latest Tango VM (Tango 9.1.0, JTango-9.0.5.jar). The sim/motor/1/StepSize attribute can be read as expected using aync read methods, but trying to subscribe to a change event (subscribe_event() method), I get an ‘fr.esrf.TangoApi.ConnectionFailed' exception, as if the attribute is not known. Same thing for most of the sim/motor attributes. However, using the ‘Position’ attribute, everything works well! Any idea? Thanks Jerome Attachments: 2Kb

# 7 years ago

Hi,

I am perhaps missing something obvious, but I am unable to subscribe a change event for some attributes.
Look at the attached example, that I run on the latest Tango VM (Tango 9.1.0, JTango-9.0.5.jar).
The sim/motor/1/StepSize attribute can be read as expected using aync read methods, but trying to subscribe to a change event (subscribe_event() method), I get an ‘fr.esrf.TangoApi.ConnectionFailed' exception, as if the attribute is not known.
Same thing for most of the sim/motor attributes. However, using the ‘Position’ attribute, everything works well!

Any idea?

Thanks
Jerome

# 7 years ago
Vatsal	Hi Jerome, The error is because the polling (necessary to send events) for the attribute stepsize is not started by default. Also you need to set Event properties (abs_change or rel_change) for attribute stepsize. Set polling and change event properties from Jive. It will resolve the issue. It works for the attribute Postion because polling and event properties for it are already set. Also, in the catch block usage of print_exception(Exception ex) method of fr.esrf.TangoDs.Except class will give more information related to exception. Stacktrace is also required as it shows how the program ended up in that place of the code. Hope this helps in resolving the issue. Regards, Vatsal Trivedi

# 7 years ago

Vatsal

Hi Jerome,

The error is because the polling (necessary to send events) for the attribute stepsize is not started by default. Also you need to set Event properties (abs_change or rel_change) for attribute stepsize. Set polling and change event properties from Jive. It will resolve the issue.

It works for the attribute Postion because polling and event properties for it are already set.

Also, in the catch block usage of print_exception(Exception ex) method of fr.esrf.TangoDs.Except class will give more information related to exception. Stacktrace is also required as it shows how the program ended up in that place of the code.

Hope this helps in resolving the issue.

Regards,
Vatsal Trivedi

# 7 years ago
jcambon	Thanks a lot Vatsal, configuring correctly the polling and event properties, everything works as expected I obviously missed these properties, although I have read carefully the Tango documentation… Regards, Jerome