Re: [Tauruslib-users] Maximum required time to update Taurus label.

[Carlos P. <cpa...@ce...>]

Hi, I just want to give some extra information about polling in Taurus:

As Sebastien said, the default polling period of taurus is 3s and can be 
changed with 

taurus.changeDefaultPollingPeriod(period_in_ms)

The above will set the taurus polling period (i.e. an active periodic 
read by the *client*). This affects to *all* attributes for the given 
client, and therefore setting it to a too short period if the client 
connects to a lot of servers may not be a good idea (note: taurus 
optimizes the polling by reading all attributes from a given device at 
once). 

But taurus polling is not the only way to go: you can use the Tango 
polling system (i.e. at server level), which can be configured 
independently for each attribute of a device via jive. See section 9.2 
of [1]. Note that in this case, the polling will be set at attribute 
level *but for all clients*.

Apart from that, it is always worth to consider programming your device 
servers to push events (see section 9.4 of [1]). This way, instead of 
periodic polling you will get updated values as soon as they change and 
you save bandwidth when the values do not change. We at Alba push events 
in devices such as motors in which we want to see very quick updates of 
the position when they are moving but which may stay at one position 
without moving for months.

Taurus handles this "intelligently" and it will only activate its own 
polling for a given attribute if neither Tango polling is active nor 
events are pushed at the server.


[1] 
http://www.esrf.eu/computing/cs/tango/tango_doc/kernel_doc/ds_prog/node10.html

I hope that helps.

Cheers,

Carlos


On Tue 7 July 2015 12:11:16 Nexeya TANGO Team wrote:
> Hi,
> 
> There is a method for changing the polling period which is 3s by
> default.
 
> You will have to insert this into your application.
> Import taurus # if it isn’t already imported
> taurus.changeDefaultPollingPeriod(500)
> 
> 
> Sébastien GARA
> Ingénieur d'études - Formateur TANGO
> NEXEYA SYSTEMS
> Une société de NEXEYA
> 24 Avenue de Pasleck
> CS 30019
> 16400 La Couronne
> ----------------------------------
> Tel: 33 (0)5.45.24.22.36
> Afin de contribuer au respect de l'environnement, merci de n'imprimer
> ce courriel qu'en cas de nécessité.
 Ce message et les fichiers
> pouvant être attachés sont confidentiels, réservés à l'usage unique
> des destinataires et n'engagent NEXEYA sous aucune forme que ce soit.
> This email and any files transmitted with it are confidential,
> intented solely for the unique use of the recipients and don't commit
> NEXEYA. 
> De : Binit Amin [mailto:bin...@tc...]
> Envoyé : mardi 7 juillet 2015 12:13
> À : tau...@li...
> Objet : [Tauruslib-users] Maximum required time to update Taurus
> label.
 
> Hello All,
> 
> I want to know, what is the maximum time taurus label takes to update
> its values, when it is connected with the device server. Because when
> I connecting my taurus label it takes little bit time to update its
> value.
 
> For checking purpose I try using one clock Programming and update
> taurus label and It's maximum of 3 sec in my system.
 Is this correct
> delay period for each system or is this time period is system
> dependent, because I had tried on other system also. and it is same. 
> If yes then is there any way to decrease that delay time to 1
> second??
 
> FYI I am using Fedora 19, PyQt 4.11.3, Python 2.7.5, PyTango 8.1.5
> Attachment includes the video of displaying delay in time because of
> refreshing period of taurus label.
 
> Any help is appreciable.
> 
> --
> Thanks & Regards
> Binit Amin
> Assistant System Engineer
> TATA Consultancy Services
> Cellno: +91-7276974159
> Mailto: bin...@tc...<mailto:bin...@tc...>
> Website: http://www.tcs.com
> 
> =====-----=====-----=====
> Notice: The information contained in this e-mail
> message and/or attachments to it may contain
> confidential or privileged information. If you are
> not the intended recipient, any dissemination, use,
> review, distribution, printing or copying of the
> information contained in this e-mail message
> and/or attachments to it are strictly prohibited. If
> you have received this communication in error,
> please notify us by reply e-mail or telephone and
> immediately and permanently delete the message
> and any attachments. Thank you

-- 
+----------------------------------------------------+
 Carlos Pascual Izarra
 Scientific Software Coordinator
 Computing Division
 ALBA Synchrotron  [http://www.albasynchrotron.es]
 Carretera BP 1413 de Cerdanyola-Sant Cugat, Km. 3.3
 E-08290 Cerdanyola del Valles (Barcelona), Spain
 E-mail: cpa...@ce...
 Phone: +34 93 592 4428
+----------------------------------------------------+